The number 6 has four different factors,1,2,3,6.What is one possible two digit integer that has exactly three different positive factors?
A number will only have an odd number of factors if it’s a perfect square. It it has only 3 factors, then it’s the square of a prime number. So pick a two-digit square of a prime number. 25 or 49 work: their factors are 1, 5, 25 and 1, 7, 49, respectively.