Final answer:
The numbers 25, 16, 49, and 81 are all perfect squares, while 63 is not a perfect square. Therefore, the number that is not like the others is 63.
Step-by-step explanation:
The student is asking to identify the number that is not like the others in the series 25, 16, 49, 63, 81. To solve this problem, we should look for a common characteristic that most of the numbers share but one does not.
Upon examination, we can see that the numbers 25, 16, 49, and 81 are all perfect squares. Specifically, 25 is 5², 16 is 4², 49 is 7², and 81 is 9². The number 63, however, is not a perfect square of any integer. Therefore, 63 is the number that is not like the others in this list.