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Mental Math: Tricks To Become A Human Calculator
You don’t have to buy this book. Just read this till the end
You don’t have to buy this book. Just read this till end & you will learn something that will change the way you do math forever. Warning: I am revealing this secret only to the first set of readers who will buy this book & plan to put this secret back inside the book once I have enough sales. So read this until the very end while you still can.
School taught you the wrong way to do math
The way you were taught to do math, uses a lot of working memory. Working memory is the short term memory used to complete a mental task. You struggle because trying to do mental math the way you were taught in school, overloads your working memory. Let me show you what I mean with an example:
Try to multiply the 73201 x 3. To do this you multiply the following:
1 x 3 =
0 x 3 =
2 x 3 =
3 x 3 =
7 x 3 =
This wasn’t hard, & it might have taken you just seconds to multiply the individual numbers. However, to get the final answer, you need to remember every single digit you calculated to put them back together. It takes effort to get the answer because you spend time trying to recall the numbers you already calculated. Math would be easier to do in your head if you didn’t have to remember so many numbers.
Imagine when you tried to multiply 73201 x 3, if you could have come up with the answer, in the time it took you to multiply the individual numbers. Wouldn’t you have solved the problem faster than the time it would have taken you to punch in the numbers inside a calculator?
Do the opposite of what you were taught in school
The secret of doing mental math is to calculate from left to right instead of from right to left. This is the opposite of what you were taught in school. This works so well because it frees your working memory almost completely. It is called the LR Method where LR stands for Left to Right.
Lets try to do the earlier example where we multiplied 73201 x 3. This time multiply from left to right, so we get:
7 x 3 = 21
3 x 3 = 9
3 x 2 = 6
0 x 3 = 0
3 x 1 = 3
Notice that you started to call out the answer before you even finished the whole multiplication problem. You don’t have to remember a thing to recall & use later. So you end up doing math a lot faster.
The Smart Choice
You could use what you learnt & apply it to solve math in the future. This might not be easy, because we just scratched the surface. I've already done the work for you. Why try to reinvent the wheel, when there is already a proven & tested system you can immediately apply.
This book was first available in video format & has helped 10,000+ students from 132 countries. It is available at ofpad.com/mathcourse to enroll. This book was written to reach students who consume the information in text format. You can use the simple techniques in this book to do math faster than a calculator effortlessly in your head, even if you have no aptitude for math to begin with.
Imagine waking up tomorrow being able to do lightning fast math in your head. Your family & friends will look at you like you are some kind of a genius. Since calculations are done in your head, you will acquire better mental habits in the process. So you will not just look like a genius. You will actually be one.
Limited Time Bonus
Weekly training delivered through email for $97 is available for free as a bonus at the end of this book for the first set of readers. Once we have enough readers, this bonus will be charged $97.
Why Price Is So Low
This book is priced at a ridiculous discount only to get our first set of readers. When we have enough readers the price will go up.
You don’t have to buy this book. Just read this till end & you will learn something that will change the way you do math forever. Warning: I am revealing this secret only to the first set of readers who will buy this book & plan to put this secret back inside the book once I have enough sales. So read this until the very end while you still can.
School taught you the wrong way to do math
The way you were taught to do math, uses a lot of working memory. Working memory is the short term memory used to complete a mental task. You struggle because trying to do mental math the way you were taught in school, overloads your working memory. Let me show you what I mean with an example:
Try to multiply the 73201 x 3. To do this you multiply the following:
1 x 3 =
0 x 3 =
2 x 3 =
3 x 3 =
7 x 3 =
This wasn’t hard, & it might have taken you just seconds to multiply the individual numbers. However, to get the final answer, you need to remember every single digit you calculated to put them back together. It takes effort to get the answer because you spend time trying to recall the numbers you already calculated. Math would be easier to do in your head if you didn’t have to remember so many numbers.
Imagine when you tried to multiply 73201 x 3, if you could have come up with the answer, in the time it took you to multiply the individual numbers. Wouldn’t you have solved the problem faster than the time it would have taken you to punch in the numbers inside a calculator?
Do the opposite of what you were taught in school
The secret of doing mental math is to calculate from left to right instead of from right to left. This is the opposite of what you were taught in school. This works so well because it frees your working memory almost completely. It is called the LR Method where LR stands for Left to Right.
Lets try to do the earlier example where we multiplied 73201 x 3. This time multiply from left to right, so we get:
7 x 3 = 21
3 x 3 = 9
3 x 2 = 6
0 x 3 = 0
3 x 1 = 3
Notice that you started to call out the answer before you even finished the whole multiplication problem. You don’t have to remember a thing to recall & use later. So you end up doing math a lot faster.
The Smart Choice
You could use what you learnt & apply it to solve math in the future. This might not be easy, because we just scratched the surface. I've already done the work for you. Why try to reinvent the wheel, when there is already a proven & tested system you can immediately apply.
This book was first available in video format & has helped 10,000+ students from 132 countries. It is available at ofpad.com/mathcourse to enroll. This book was written to reach students who consume the information in text format. You can use the simple techniques in this book to do math faster than a calculator effortlessly in your head, even if you have no aptitude for math to begin with.
Imagine waking up tomorrow being able to do lightning fast math in your head. Your family & friends will look at you like you are some kind of a genius. Since calculations are done in your head, you will acquire better mental habits in the process. So you will not just look like a genius. You will actually be one.
Limited Time Bonus
Weekly training delivered through email for $97 is available for free as a bonus at the end of this book for the first set of readers. Once we have enough readers, this bonus will be charged $97.
Why Price Is So Low
This book is priced at a ridiculous discount only to get our first set of readers. When we have enough readers the price will go up.
172 pages, Kindle Edition
Published October 18, 2017
708 people are currently reading
324 people want to read
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Displaying 1 - 27 of 27 reviews
January 8, 2018
I got this book for my daughter since she was having trouble in math. At first, it was hard to explain since I myself aren't that good at math but we slowly caught on the more we went on. I'm not going to say we are experts now but this is one of the few guides that actually made an impact.
November 17, 2025
only skimming through it. Read about digit sum and then saw it's 90% success only 😒 . mentioned about DD has great accuracy but didn't check it . continued skimming and thought this too won't be helpful
then stem technique seems useful. so read about it and traced back and learned LR method with rounding up and factoring techniques and finding how much u rounded technique.
I already used rounding up technique for multiplication without knowing about it. but i don't think i used rounding up with (-).
Then only learned squaring method. others are neither seems easy nor interesting.😮💨
takeaways:
Eg: 43 * 23
43 is the multiplicand. It is the number being multiplied.
23 is the multiplier. It is the number which is multiplying the first number
1. Multiplication By 11 (not at all interested in learning tricks for calculation with specific numbers but it's just so easy i learned in a single glance of reading these 3 steps 😗)
Step 1 - The first number of the multiplicand (number multiplied) is put down as the left-hand number of the answer.
Step 2 - Each successive number of the multiplicand is added to its neighbour to the left.
Step 3 - If the addition results in two figures, carry over the 1 (Note: The two figure number will never be more than 18 (got by adding 9+9)).
Step 4 - The last number of the multiplicand becomes the right-hand number of the answer.
2. LR method
The secret to doing mental math is to calculate from left to right instead of from right to left
3. LR method ith Rounding Up:
Finding how much u rounded up: (e: 465 -> rounding up as 500-35; how much rounded up is 35)
The last digits add up to 10.
The remaining digits add up to 9.
Addition:
Step 1 - Round up a number.
Step 2 - Add from left to right to the amount you rounded-up.
Step 3 - Subtract the amount you rounded-up from the sum
Rounding up should only be done when you have to carry over a lot of numbers.
If you don’t have to carry over any number or if you have to carry over just one-digit, you will end up complicating the problem by rounding up.
Subtraction:
Step 1 - Round up the second number.
Step 2 - Subtract from left to right the amount you rounded-up to.
Step 3 - Add the amount you rounded-up with the subtracted amount
Rounding up before calculating is usually more useful for subtraction than it is for addition.
Rounding up should only be done when you have to borrow a lot of numbers for subtraction just like how you had to carry over a lot of numbers for addition.
Remember to only round up when you have to borrow numbers. If you don’t have to borrow any number you will be better off doing the subtraction without rounding up
Multiplication:
Step 1 - Break the multiplier.
Step 2 - Multiply from left to right.
Step 3 - Multiply the amount you rounded-up.
Step 4 - Add the individual answers together
LR Multiplication With Round Up
Rounding up and multiplying is also useful for two-digit multipliers when the numbers end in 7, 8 or 9.
Step 1 - Round up a number.
Step 2 - Multiply the rounded-up value and the amount you rounded-up from left to right. Step 3 - Subtract the two numbers.
LR Multiplication After Factoring:
Factoring a number means breaking it down into one-digit numbers, which when later multiplied together will give the original number.
For example, 48 can be factored as 6 x 8 or 12 x 4. However, we will prefer to use single digit factors as the intention of factoring the numbers is to simplify the multiplication.
Step 1 - Factor one of the numbers.
Step 2 - Multiply the number with the first factor (left to right)
Step 3 - Multiply the product with the second factor (left to right).
4. Stem multiplication:
Step 1 - Decide a stem number.
Step 2 - Find the difference of the stem number from the multiplicand and the multiplier. Step 3 - Add the multiplicand with the difference of the multiplier OR add the multiplier with the difference of the multiplicand. (Note: Both differences will give the same result).
Step 4 - Multiply the stem number with the result of the addition.
Step 5 - Multiply the difference of the stem number from the multiplicand with the difference of the stem number from the multiplier.
Step 6 - Add the products of the last two steps to get your final answer.
It is recommended that you try to use 10 or 100 first. If that does not simplify the problem, next try to use 20 or 50. If you cannot use these numbers, you can use 30 and 40 followed by the other multiple of 10.
when the numbers are further away from each other, the intermediate steps might be a little harder to do but you should easily be able to do the intermediate calculation with the LR Method.
5. Squaring Numbers Ending With 5
Step 1 - Multiply the first digit with the next higher digit to get the first few digits of the answer.
Step 2 - Attach 25 to the first few digits of your answer to get the full answer.
Squaring Any Number
Step 1 - Round the number up or down to the nearest multiple of 10.
Step 2 - If you rounded-up, subtract the number by the amount by which you rounded-up. If you rounded-down, add instead of subtract.
Step 3 - Multiply the numbers from the previous two steps.
Step 4 - Square the amount you rounded-up/down and add it to the number from the previous step.
Tips:
When initially solving the problems, practice the problems by saying it out loud. Saying something out loud will serve as an additional memory aid which clears up more of your working memory.
then stem technique seems useful. so read about it and traced back and learned LR method with rounding up and factoring techniques and finding how much u rounded technique.
I already used rounding up technique for multiplication without knowing about it. but i don't think i used rounding up with (-).
Then only learned squaring method. others are neither seems easy nor interesting.😮💨
takeaways:
Eg: 43 * 23
43 is the multiplicand. It is the number being multiplied.
23 is the multiplier. It is the number which is multiplying the first number
1. Multiplication By 11 (not at all interested in learning tricks for calculation with specific numbers but it's just so easy i learned in a single glance of reading these 3 steps 😗)
Step 1 - The first number of the multiplicand (number multiplied) is put down as the left-hand number of the answer.
Step 2 - Each successive number of the multiplicand is added to its neighbour to the left.
Step 3 - If the addition results in two figures, carry over the 1 (Note: The two figure number will never be more than 18 (got by adding 9+9)).
Step 4 - The last number of the multiplicand becomes the right-hand number of the answer.
2. LR method
The secret to doing mental math is to calculate from left to right instead of from right to left
3. LR method ith Rounding Up:
Finding how much u rounded up: (e: 465 -> rounding up as 500-35; how much rounded up is 35)
The last digits add up to 10.
The remaining digits add up to 9.
Addition:
Step 1 - Round up a number.
Step 2 - Add from left to right to the amount you rounded-up.
Step 3 - Subtract the amount you rounded-up from the sum
Rounding up should only be done when you have to carry over a lot of numbers.
If you don’t have to carry over any number or if you have to carry over just one-digit, you will end up complicating the problem by rounding up.
Subtraction:
Step 1 - Round up the second number.
Step 2 - Subtract from left to right the amount you rounded-up to.
Step 3 - Add the amount you rounded-up with the subtracted amount
Rounding up before calculating is usually more useful for subtraction than it is for addition.
Rounding up should only be done when you have to borrow a lot of numbers for subtraction just like how you had to carry over a lot of numbers for addition.
Remember to only round up when you have to borrow numbers. If you don’t have to borrow any number you will be better off doing the subtraction without rounding up
Multiplication:
Step 1 - Break the multiplier.
Step 2 - Multiply from left to right.
Step 3 - Multiply the amount you rounded-up.
Step 4 - Add the individual answers together
LR Multiplication With Round Up
Rounding up and multiplying is also useful for two-digit multipliers when the numbers end in 7, 8 or 9.
Step 1 - Round up a number.
Step 2 - Multiply the rounded-up value and the amount you rounded-up from left to right. Step 3 - Subtract the two numbers.
LR Multiplication After Factoring:
Factoring a number means breaking it down into one-digit numbers, which when later multiplied together will give the original number.
For example, 48 can be factored as 6 x 8 or 12 x 4. However, we will prefer to use single digit factors as the intention of factoring the numbers is to simplify the multiplication.
Step 1 - Factor one of the numbers.
Step 2 - Multiply the number with the first factor (left to right)
Step 3 - Multiply the product with the second factor (left to right).
4. Stem multiplication:
Step 1 - Decide a stem number.
Step 2 - Find the difference of the stem number from the multiplicand and the multiplier. Step 3 - Add the multiplicand with the difference of the multiplier OR add the multiplier with the difference of the multiplicand. (Note: Both differences will give the same result).
Step 4 - Multiply the stem number with the result of the addition.
Step 5 - Multiply the difference of the stem number from the multiplicand with the difference of the stem number from the multiplier.
Step 6 - Add the products of the last two steps to get your final answer.
It is recommended that you try to use 10 or 100 first. If that does not simplify the problem, next try to use 20 or 50. If you cannot use these numbers, you can use 30 and 40 followed by the other multiple of 10.
when the numbers are further away from each other, the intermediate steps might be a little harder to do but you should easily be able to do the intermediate calculation with the LR Method.
5. Squaring Numbers Ending With 5
Step 1 - Multiply the first digit with the next higher digit to get the first few digits of the answer.
Step 2 - Attach 25 to the first few digits of your answer to get the full answer.
Squaring Any Number
Step 1 - Round the number up or down to the nearest multiple of 10.
Step 2 - If you rounded-up, subtract the number by the amount by which you rounded-up. If you rounded-down, add instead of subtract.
Step 3 - Multiply the numbers from the previous two steps.
Step 4 - Square the amount you rounded-up/down and add it to the number from the previous step.
Tips:
When initially solving the problems, practice the problems by saying it out loud. Saying something out loud will serve as an additional memory aid which clears up more of your working memory.
April 9, 2018
Incomplete, lacks many concepts
Most of the tricks used are based on Vedic maths with no mention of this technique.
Some methods suggested for faster calculations take longer time than doing it with old school method.
Otherwise, good for basic multiplication and addition.
One can find many more methods and free videos of youtube. (Instead of going for the paid video series version of this book ,advertised within ).
Most of the tricks used are based on Vedic maths with no mention of this technique.
Some methods suggested for faster calculations take longer time than doing it with old school method.
Otherwise, good for basic multiplication and addition.
One can find many more methods and free videos of youtube. (Instead of going for the paid video series version of this book ,advertised within ).
December 26, 2017
Not impressive at all
I had high expectations on this book which claim to teach some tricks that readers have never saw before. However, most of them turned out just to be normal tricks that I learned in second or third grade. Besides, It is not worth the effort to practice. There are not much situations you can show off some two or three digits calculation.
I had high expectations on this book which claim to teach some tricks that readers have never saw before. However, most of them turned out just to be normal tricks that I learned in second or third grade. Besides, It is not worth the effort to practice. There are not much situations you can show off some two or three digits calculation.
November 6, 2017
There are many books on doing mental math out there that has no practical relevance. You will be taught tricks to solve problems that you will never encounter in real life. This will make you wonder why should you even bother learning it. However, this book is not like that. The stuff taught in this book is not usually taught in school and some of the chapters make you wonder why it was never a part of your education. We wouldn't rely on the calculator so much if they taught this in school. The techniques are not complicated or hard to do, but some of the later chapters will take some practice.
December 27, 2017
I really liked this book! Dense, useful, and practical. It does exactly what it promises - to do math in mind, easier and faster.
Myself, I like numbers, but when it comes to computing, I prefer to use a calculator. Because of this habit, I lost the ability to do even simple additions. I got lazy. And then worse, I felt stupid and embarrassed not being able to sum 136+237 without a calculator or a piece of paper. It seemed too complex that I gave up.
Thanks to this book and tricks it reveals, I can easily sum up three digits numbers. My head won't hurt and I won't feel like a retard :)
Thanks to the authors of "Mental Math" who wrote such a useful book!
Myself, I like numbers, but when it comes to computing, I prefer to use a calculator. Because of this habit, I lost the ability to do even simple additions. I got lazy. And then worse, I felt stupid and embarrassed not being able to sum 136+237 without a calculator or a piece of paper. It seemed too complex that I gave up.
Thanks to this book and tricks it reveals, I can easily sum up three digits numbers. My head won't hurt and I won't feel like a retard :)
Thanks to the authors of "Mental Math" who wrote such a useful book!
December 23, 2017
Great and clear instruction!
This was a weird one for me, I don’t normally read or buy these kinds of ebooks, but I’m glad to report that I am in no way disappointed.
As the author says in the introduction, he was bad with math too once upon a time. This made me feel at ease immediately and let me know that it’s okay, if he can do it, I can too!
The instructions were clear and simplified and the author lays out every step, but still gives you the chance to test your new skills throughout.
This is something I will use in everyday life!
This was a weird one for me, I don’t normally read or buy these kinds of ebooks, but I’m glad to report that I am in no way disappointed.
As the author says in the introduction, he was bad with math too once upon a time. This made me feel at ease immediately and let me know that it’s okay, if he can do it, I can too!
The instructions were clear and simplified and the author lays out every step, but still gives you the chance to test your new skills throughout.
This is something I will use in everyday life!
December 23, 2017
This is a useful book for students who are going to go into college
The author did a great job. I bought this book because I'm ready to go back into college, and I felt that I needed to do some quick lessons on my math. I came across this book.
The intro story is universal because that's how a lot of us feel today before going into college, I certainly do. But going through this book helped me see some basic patterns to math. I'll refer back to this book while I'm advancing in my courses this year.
The author did a great job. I bought this book because I'm ready to go back into college, and I felt that I needed to do some quick lessons on my math. I came across this book.
The intro story is universal because that's how a lot of us feel today before going into college, I certainly do. But going through this book helped me see some basic patterns to math. I'll refer back to this book while I'm advancing in my courses this year.
January 24, 2021
This is a tricky review for me. Because it has amazing content, it really changed the way I'm going to handle mental calculations from now on, but it also has some tips that I didn't find really useful and I believe the writing style, while not poor, could be vastly improved.
Still, I'd recommend this book. I wouldn't know if there are better books about the subject, but changing my mental model to calculate left-to-right rather than right-to-left was a small epiphany, and for that I'm really grateful.
Still, I'd recommend this book. I wouldn't know if there are better books about the subject, but changing my mental model to calculate left-to-right rather than right-to-left was a small epiphany, and for that I'm really grateful.
November 10, 2017
MATH....A GREAT INNOVATIVE WAY TO LEARN IT...
This is a rather unique book offering you how to do math calculations in record time...A short book but one packed with plenty of knowledge and understanding of how math is taught and how it should be taught...the author takes you step by step on how to do each type of calculation....encouraging to try it and inferring you practice worksheets and correct answers at the end of each chapter...if you have problems understanding you can contact him...there is an online course to take if you feel a need to have visual and auditory teaching...not only recommend for teachers at all levels but you the general public...
This is a rather unique book offering you how to do math calculations in record time...A short book but one packed with plenty of knowledge and understanding of how math is taught and how it should be taught...the author takes you step by step on how to do each type of calculation....encouraging to try it and inferring you practice worksheets and correct answers at the end of each chapter...if you have problems understanding you can contact him...there is an online course to take if you feel a need to have visual and auditory teaching...not only recommend for teachers at all levels but you the general public...
February 5, 2018
Great math techniques
I love that some methods of multiplication were demonstrated, to give variety if one did not find a method intuitive. The book seemed straightforward but addition seemed as easy left-to-right as right-to-left. There were some missing articles that might have made the writing clearer in such a technical topic. Yet, I like playing with numbers as well as learning new ways to perform operations.
I love that some methods of multiplication were demonstrated, to give variety if one did not find a method intuitive. The book seemed straightforward but addition seemed as easy left-to-right as right-to-left. There were some missing articles that might have made the writing clearer in such a technical topic. Yet, I like playing with numbers as well as learning new ways to perform operations.
November 5, 2017
I was able to finish this book pretty quickly and it was an easy read. I learned several things that nobody ever taught me when I was young. The first chapter on checking the claculation itself was an eye opener for me. However, this is a book on math. And it's a book you must work through and not really read to get the most out of.
November 19, 2017
Wow! Math is never been a thing for me but i think with this book and what i've learned here. i can actually like Math. great job on the explaining the different types of math problems. it took me a while since i'm not a math person myself. But i think with more practice and using of your book. i could actually learn something lol great all around. :)
November 30, 2017
I liked the way author started with his own story of his struggle with the maths... the book covers how to win your anxiety over math superbly...the methods explained in the book were quite new to me...the concepts are explained well with detailed examples..this book will help my kids too to learn the innovative ways to understand maths.. well written book..
January 5, 2020
At first my son and I didn’t think this was much of anything, adding and subtracting large numbers from left to right instead of right to left, but once we got to the tricks for multiplying 2 digit numbers and squaring, then it became neat and fun for us to test and practice this while traveling on vacation. He’ll be able to use it to impress his math club friends say school!
November 12, 2017
Helpful
This book is going to be so helpful. I know most people think once you graduate math isn’t necessary but with two kids and a second masters program, I need all the help I can get. This is definitely going to stay in my library to refer back to.
This book is going to be so helpful. I know most people think once you graduate math isn’t necessary but with two kids and a second masters program, I need all the help I can get. This is definitely going to stay in my library to refer back to.
December 27, 2017
I liked reading this book, which reconciled me with math. It offers a lot of tricks and techniques easy to understand and very useful. I recommend it to people who dream to calculate like computers or simply want to improve their mathematical level.
February 10, 2018
Squaring technique is not good
This book is not at all good instead of making things simple and easier things are made complex and confusing there is far better and easier way to square a number than given in this book
This book is not at all good instead of making things simple and easier things are made complex and confusing there is far better and easier way to square a number than given in this book
September 29, 2018
Nothing special about it. Some methods could take longer than the conventional way to go about it. Some concepts I already knew from the school of vedic maths. Some methods that the author claims to be mathematical tricks are only the distributive and associative multiplication properties.
November 12, 2017
Easy and quick methods
I bought this book for my son, the methods explained in a very easy way and , helpful book
Must have for everyone
I bought this book for my son, the methods explained in a very easy way and , helpful book
Must have for everyone
January 11, 2018
Even though math has always been my strongest subject, I learned a lot of useful tricks from reading this book.
February 4, 2018
Interesting reminders
Summary of basic arithmetic skills learnt under British syllabi of the 1950s.
Valuable and very useful if used regularly in day to day activities
Summary of basic arithmetic skills learnt under British syllabi of the 1950s.
Valuable and very useful if used regularly in day to day activities
February 20, 2018
Must read
Excellent book
Must read
Methods are explained in simple way
Good techniques
Good read for all age group
Worth purchasing
Excellent book
Must read
Methods are explained in simple way
Good techniques
Good read for all age group
Worth purchasing
July 30, 2018
It's good.
Good for price. There are better ways for me but liked it. This is making !e write more words. Ok.
Good for price. There are better ways for me but liked it. This is making !e write more words. Ok.
Read
August 5, 2019speed maths
This entire review has been hidden because of spoilers.
March 6, 2025
My skills actually improved dramatically.
October 30, 2022
I like the book, I found LR method does improve the calculation speed. Book is also easy to read. definitely one needs to practice. However I spotted a few errors in calculation. Maybe errors are already fixed in newer version but sharing anyway,
In LR subtraction with rounding up section, subtraction exercise answer "1" and "11" are wrong. Author might need to update those. I wonder how reviewers missed those. :)
In LR subtraction with rounding up section, subtraction exercise answer "1" and "11" are wrong. Author might need to update those. I wonder how reviewers missed those. :)
Displaying 1 - 27 of 27 reviews