Originally Posted by

**jstarks44444** Hey all, I would really appreciate some help with the following:

Let n = the sum from i=0 to v(n)-1 of x-sub-i * 10^i, where each x-sub-i is a digit.

n "is the same as" x-sub-0 (mod 2)

Well I get this one by doing the following:

n = x-sub-(v(n)-1)*10^(v(n)-1) + x-sub-(v(n)-2)*10^(v(n)-2) + ... + x-sub-0 * 10^0

but 10 is the same as 0 (mod 2) so 10^j is the same as 0^j

so n is the same as x-sub-0 (mod 2)

But how can I prove that:

n is the same as x-sub-0 + 10*(x-sub-1) (mod 4)

n is the same as x-sub-0 + 10*(x-sub-1) + 100*(x-sub-2) (mod 8)

n is the same as x-sub-0 (mod 5)