# Unit Digit

1. Dec 2, 2003

### PrudensOptimus

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

$$a^b$$

where a, b, are positive integers?

2. Dec 2, 2003

### Hurkyl

Staff Emeritus
Yes.

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

3. Dec 2, 2003

### PrudensOptimus

U mean a pattern?

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

4. Dec 2, 2003

### Hurkyl

Staff Emeritus
I mean something a little more rigorous.

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

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