Volume of a Pyramid

How do you find the volume of a square pyramid with base edges of 21 feet
and a height of 18 ft?

Volume of a Pyramid
1/3 x (area of base) x height
= 1/3 x (21 x 21) x 18 {the base is a square with an area of 21 x 21} 
= 1/3 x 441 x 18 {multiplied 21 by 21}
= 1/3 x 7938 {took 441 x 18}
= 2646 ft3{divided 7938 by 3}

- Algebra House