This question seems odd a little bit.
We have a range of figures expressed \((10^n-1)^n\), where we are given first three elements n=1, n=2, n=3.
Then I am asked what is the last digit of given range of figures.
in 2) it is mentioned that n is prime, I know that all primes are odd except for 2. But I see that n=2 is in range and a set \((10^n-1)^n\) has already n=1, n=2, n=3, so last figure can not contain \((10^2-1)^2\). Additional n=2 misleads.
Don't you think that for clarity we must add something like " n can be any number" or something like this.
Audaces fortuna juvat!
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