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.

## Comments (2)

i thought you will use the factors of 6 to form the two digit integer(it’s a question 15)…why not?

This is a question you have to answer for yourself. You misread the question. What word or phrase did you not comprehend?