Code: SN
P=1000
1000b+a = 8*125b+a = a (mod 8)
Formulae:
Number N is divisible by 8 iff least significant digit is divisible by 8
Example:
N = 3 459 637 480 is divisible by 8 due 480=8*60.
N = 123 459 071 isn't divisible by 8.
Code: PU
P=10, (k=2)
10b+a = 2b+a
Formulae:
Number N is divisible by 8 iff 2b+a is divisible by 8.
Example:
Number N = 25712
2( 2571)+2 =
2(2( 257+1)+2 =
2(2(2( 25+7)+1)+2 =
2(2(2(2*2+5)+7)+1)+2 =
2(2(2* 1+7)+1)+2 =
2(2* 1+1)+2
2* 3+2 = 0 (mod 8)
is divisible by 8.
