Question

Use euclid's division lemma to show that the cube of any positive integer is of the form 9M 9M + 1 or 9M + 8
In this question we take b= 3 but whyyyyy?????
Why we don't take b=9

Answer 1

If b is taken as 9, then the sum becomes too long. Then,

r = 0,1,2,3,4,5,6,7,8

Answer 2

if we take b it becomes very long process

r=1,2,3,4,5,6,7,8