last digit of square of a no. can't be 2

If the last digit of n is 1, the last digit of n^2 is 1^1=1

If 2 then 4

3:9

4:6 (since 4^2=16)

5:5

6:6

7:9

8:4

9:1

0:0

Huh, seems like no matter what the last digit is, when we square the number, the last digit is never going to be 2