720/2 = 360
360/2 = 180
180/2 = 90
90/2 = 45
45/3 = 15
15/3 = 5
5/5 = 1
720 = 2 * 2 * 2 * 2 * 3 * 3 * 5
You need to use the numbers above: 2, 2, 2, 2, 3, 3, 5
720 has no factor of 7, so don't use 7.
If you follow a path that has a 4, that counts as 2, 2
If you use a 6, that is the same as 2, 3.
