**Problem 323**

What characteristic do the numbers 8, 10, 15, 26, and 33 have that the numbers 5, 9, 16, 18, and 24 don’t have? (Hint: List factors of the numbers.) Give two more numbers that have this characteristic.

**Solution**

Numbers of factors are same in case of first group,

8=1,2,4,8

10= 1,2,5,10

15=1,3,5,15

26=1,2,13,26

In seconds group, all number have different number of factors

5=1,5

9=1,3,9

16=1,2,4,8,16

18=1,2,3,9,18

24=1,2,3,6,8,12,24

Two more numbers are 20=1,2,4,5,10,20 and 30=1,3,5,10,15,30 both have same number of factors.