Last one digit

We can say that for any

$5^n = 5 (\text{mod 10}$ ) where n is any Positive integer.

So For $5^{2n} = 5 (\text{mod 10}$ ) or $25^{n} = 5 (\text{mod 10}$ ).

So for n=10 we get

$25^{10} = 5 (\text{mod 10}$ )

So Last digit is $\boxed{5}$