How many times in one life can a person have a birthday that is both a perfect square and a perfect fourth power?

Question

please show me the thinking behind this

Answer 1

Here is a way, Anastasia. Assume 100 as a possible lifetime. Or take the expected lifetime of a man or woman. Then consider the fourth powers of numbers to be equal to perfect squares. The latter set is 1,4,9, 16, 25 and so on. The former set is 1, 16, 81, 256. Seems that we only have a few: 1, 16, 81 (maybe). 256 is not likely. So the answer is either 2 or 3, depending on where you decide to put the maximum age.