Cat #1 Q9, Digit Duplication

[Gena]

In the explanation
1) What does it means by unit digit.
Also, in the first statement, it says unit digit of X4 is 1 but why in the explaination also talks about x4 could be 81 and so on?
If x4 is 1, wouldn't x2 is also equal to 1? Because if X=1, then X2 is 1 and X4 also 1.

Thank you.

[esledge]

Please read the "sticky" of posting guidelines for this folder. The exam and question number are different for everyone, so we can only identify questions by text.

There are other guidelines, but this is most applicable:

"2) Use the first five to eight words of the problem as your Subject heading. Also, post the entire text of the question and answer choices. Do not use abbreviations."

Looking forward to helping once you repost. Thanks!