The ladder forms a right angle triangle with the building and the ground. The length of the ladder represents the hypotenuse of the right angle triangle. The height, h from the top of the ladder to the base of the house represents the opposite side of the right angle triangle.
The distance from the foot of the ladder to the base of the house represents the adjacent side of the right angle triangle.
To determine the height, h that the ladder reaches, we would apply Pythagoras theorem which is expressed as
Alright, so you have to have heads and tails, as well as 3 spots each for each even number. Therefore, we need heads with 2 4 6 as well as tails with 2 4 6 (the third one down in the first picture)