Question

Cannon balls for an antique cannon are stacked next to it in four layers to form a square pyramid. How many cannon balls are in a pryimad

Answer 1

the amount of balls in a given layer can be found by squaring the layer it is in

4 layers
top layer (1st) is 1
2nd is 4
3rd layer is 9
4th is 16

add them up
1+4+9+16=30

30 in that pyramid