Contents: Number System; Congruencies And Its Basic Properties; Algebraic Congruences And Primitive Roots; Arithmetic Functions; Farey Sequence, Continued Fraction, Pell S Equations; Quadratic Residues, Levender S Symbols, Jacobi S Symbols; Homogeneous Quadratic Diophantine Equation; Some Number Theoretic Problems Related To Mathematics Olympiads; Answers; Etc.