鸽巢原理的问题,是英文,请见谅howmanynumbermustbeselectedfromtheset{1,2...,30}toguaranteethatatleastoneofthesenumbersisequaltothesquareofanotherselectednumber

Question

鸽巢原理的问题,是英文,请见谅
how many number must be selected from the set {1,2...,30}to guarantee that at least one of these numbers is equal to the square of another selected number

Answer 1

for there are 5 number which is the square of another selected number,they are 1,4.9,16,25,so there are at least 26 nunbers which wust be selected.