Question

Cannonballs are stacked in a pyramid shape with a triangular base of 5 cannonballs on a side.How many cannonballs in all are in the stack

Answer 1

There will be 35 cannonballs in the stack.

Explanation:

Cannonballs are stacked in a pyramid shape with a triangular base of 5 cannonballs on a side.

The top or first layer will have a single cannonball = 1

The second layer down is a triangle that will have
`1+2=3` cannonballs

The third layer will have
`1+2+3= 6` cannonballs

The fourth layer will have
`1+2+3+4 =10` cannonballs

The fifth or bottom layer will have
`1+2+3+4+5=15` cannonball

Adding those all these we get;

`1+3+6+10+15=35` cannonballs

Hence, there are 35 cannon balls in the stack.