Blade7658:
Here is the 40 for those that favor visuals. The number represent how many of each size there are. Mantis linked a good YouTube video as well.
Blade, great illustration.
Alosso, this is how I counted them. 16 + 8 1x1=24, 9 + 2 2x2=11, 4 3x3, and 1 4x4, for a total of 40...make sense now? I lumped the large and small 1x1 together and the large and small 2x2 together.