Math
posted by Emma .
Is 28851 a prime number?

It is divisible by 3:
10 Mod 3 = 1 >
10^n Mod 3 = 1^n = 1 >
Sum over cn 10^n Mod 3 =
Sum over cn Mod 3
28851 Mod 3 = (2 + 8 + 8 + 5 + 1) Mod 3
= 0 

nope, it is divisible by 3