66 33,2 11,3,2
a factor tree is this= 66 / \ 6 • 11 / \ 2 •3
66 33,2 11,3,2 There's no formula. Just divide your number and its factors by prime numbers until all the factors are prime.
The prime factors of 66 are: 2, 3 and 11
66 33,2 11,3,2
66 33,2 11,3,2
66 33,2 11,3,2
66 33,2 11,3,2
66 33,2 11,3,2
66 33,2 11,3,2
11
66 33*22 11*6