Use a factor tree.
1023
341,3
31,11,3
456
18 9,2 3,3,2
13 is already prime. Just write it down.
5 x 13 = 65 To show work, divide 65 by 5.
Divide by 3 or 5. 3 x 5 = 15
48 24,2 12,2,2 6,2,2,2 3,2,2,2,2
520 = 2 × 2 × 2 × 5 × 13
Use a factor tree. 78 39,2 13,3,2
Use a factor tree. 36 18,2 9,2,2 3,3,2,2
45 Divide by three. 15,3 Divide by three. 5,3,3 Stop.
23 is already prime.
1001 / 7 = 143 143 / 11 = 13 so prime fact. is 7 x 11 x 13