Unit Digit

[PrudensOptimus]

Hi, is there any way to find Unit Digit of a expression, say

a^b


where a, b, are positive integers?

[Hurkyl]

Yes.

Hint: fix a, vary b, and ignore the irrelevant details, see if you can find a clue...

[PrudensOptimus]

U mean a pattern?

Like 2^2 = 4, like 2^2222 = 4? Because 2222 is divisible by 2?

[Hurkyl]

I mean something a little more rigorous. [:)]

Consider the values of 2^1, 2^2, 2^3, ...