A 3-digit number xyz is squared, which of the following could be the last digit of the square?

The last digit of a square of a number depends on the last digit of the original number. Here are the possibilities:

• If the last digit of the original number is 0, 1, 5, or 6, the last digit of the square will be the same (0, 1, 5, or 6 respectively).
• If the last digit of the original number is 2 or 8, the last digit of the square will be 4.
• If the last digit of the original number is 3 or 7, the last digit of the square will be 9.
• If the last digit of the original number is 4 or 6, the last digit of the square will be 6.

So, the last digit of the square of a 3-digit number could be 0, 1, 4, 5, 6, or 9.