A grocer stacks oranges in a four-sided pyramid that is 6 layers high. Solve for the number of oranges in the pile.

A. 36

B. 546

C. 105

D. 91

Each layer contains the square of the layer number.

So,

Let's figure out:

1 squared = 1

2 squared = 4

3 squared = 9

4 squared = 16

5 squared = 25

6 squared = 36

Hence,

The total number of oranges in the pile = 1+4+9+16+25+36

= 91 oranges

D. 91