Question

Find the modulo class to which the number belongs for the given modulo system. 87, mod 8
A. 5

B. 6

C. 0

D. 7

Answer 1

D:7

To find this you need to know the remainder of 87/8. This is 7 (because 8*10 = 80, + 7 = 87).

A good way to think about these quickly is if you divide 88/8, it divides perfectly. So, 87 is just 1 down from 88, so it must belong to the class that is 1 down from 8 (for 7)

If you think about it also:, if you keep adding 8 to the sums of 7, you'll get 87.
{7, 15, 23, 31, 39, 47, 55, 63, 71, 79, 87}

Answer 2

(so 7)*