Question

You decide to build a pyramid out of wooden blocks. Each block must rest on the corners off 4 other blocks. If there is one block on top and 36 on the bottom, what is the total number of blocks you will need to complete the pyramid?

Answer 1

The top layer has 1 block
the 2nd layer from the top has 4 blocks
the 3rd layer from the top has 9 blocks
the 4th has 16 blocks
the 5th has 25 blocks, and
the 6th has s36 blocks

So we have 1+4+9+16+25+36
= 91

btw, there is a formula for the sum of squares of the first n numbers
sumofsquares(n) = n(n+1)2n+1)/6
sumofsquares(6) = 6(7)(13)/6 = 91