- 04 Jul '08 15:11

We only need to know modulos for 2, 5, and 9, right? If all 3 are zero for the numerator, then we have a natural number.*Originally posted by FabianFnas***Is [b](19^92 - 91^29) / 90**a natural number or not?

Motivate well...[/b]

**2**- Odd minus odd.*ZERO***5**- Cycles in 4, 4^4 - 1^1 = 15,*ZERO***9**- Cycles in 6, 1^2 - 1^5 = 0,*ZERO*

Since all 3 are zero, the difference is divisible by 90..

(Ignore this math) 3*92 = 276, 4.8*29 = 139.2, 276 - 48 = 228, estimate value has 22-23 digits in it and is positive..