Step by step
The question
Question: find the volume of a pyramid with a square base 12 cm by 12 cm and height 10 cm.
1 Area of the base
The base is a square, 12 by 12.
Its area is side times side: A = 12 × 12.
12 times 12 is 144.
So the base is A = 144 cm².
2 A third of the box
Draw a box around the pyramid, with the same base and the same height.
Fill the pyramid with sand 3 times.
That fills the box exactly.
So the pyramid is one third of the box.
The box is A times height.
So the pyramid is V = ⅓ × A × height.
Now put the numbers in: A = 144 and height = 10.
Keep the numbers small: divide 144 by 3 first.
144 divided by 3 is 48.
So V = 48 × 10.
48 times 10 is 480.
So the volume is 480 cm³.
Let's look back.
First: area of the base.
Last: a third of the box.