Why is 48 not a perfect square?

Answer 1

That simply means that there is no whole number which, when squared, gives you 48. Try it out - you'll quickly see that there there are two consecutive whole numbers, such that, if you square one you get LESS than 48, if you square the next one, you get MORE.

Answer 2

Because its square root isn't an integer. 6 x 6 = 36, 7 x 7 = 49