Question

Caleb made a stack of popcorn balls on a table. He placed 16 on a table then added three more layers on top of them. Each layer had four fewer balls than the previous layer. How many popcorn balls were in all in the stack

Answer 1

16 popcorn balls  1st layer                             16+12+8+4 = 40 popcorn balls in the
12 popcorn balls 2nd layer                                         stack.
8 popcorn balls 3rd layer
4 popcorn balls 4th layer

Answer 2

Hi! So if we lay out 16 popcorn balls, and each time we take away four, this is what would happen gradually,

16 bottom + 12 1st layer + 8 2nd layer + 4 3rd layer

16+12+8+4 = 40 popcorn balls!

( don't forget to use lables)