Because 45 is not a factor of 60.
30 15,2 5,3,2
30 15,2 5,3,2
30 15,2 5,3,2
The last branch of any factor tree of 30 will always be 2, 3 and 5 in some order.
30 15,2 5,3,2
Use a factor tree. 30 15,2 5,3,2
30 3 10 2 5 3, 2 and 5
30 / \ 2 15 / \ 3 5 / \ 5 1
Jenna lists all the multiple of 9
30 / 2 = 15 15 / 3 = 5
The square root of 900 is 30 and it is a factor of 900