It's just dividing out the factoring to their simplest form.
The bold numbers are the answers that go in the circles.
1. 16 < 8 and 2
8 < 2 and 4
4 < 2 and 2
2. 42 < 14 and 3
14 < 7 and 2
3. 40 < 2 and 20
20 < 10 and 2
10 < 2 and 5
4. I'm not able to see the rest of the factoring tree
