[INST] Name the greatest whole number less than 100 that has an odd number of positive factors./n [/INST]  ###Response: To find the greatest whole number less than 100 that has an odd number of positive factors, we need to find a perfect square. It can be proved that if a number is not a square number, then it will have an even number of factors. However, if a number is a perfect square, then it will have an odd number of factors. The greatest perfect square less than 100 is 81, so 81 is the greatest whole number less than 100 that has an odd number of positive factors.