MATHmaniac aka CrUNchy

Definition of Congruences:
Let n be a fixed point positive integer.
Two integers a and b are said to be congruent modulo n if na-b,symbolized by;

Example :
Any number divide by 6, the remainder will either be 0,1,2,3,4,5, or 6. We divided into 6 classes when measure by 6:

Class 1 = {…,-18,-12,-6,0,6,12,18,…}
Class 2 = {…,-17,-11,-5,1,7,13,19,…}
Class 3 = {…,-16,-10,-4,2,8,14,20,…}
Class 4 = {…,-15,-9, -3,3,9,15,21,…}
Class 5 = {…,-14,-8,-2,4,10,16,22,…}
Class 6 = {…,-13,-7,-1,5,11,17,23,…}

Set of least nonnegative residue modulo 6= {0,1,2,3,4,5,6}
>>members of the same class are congruent to each other ;