Volume of cylinder radius 3 height 5

Step by step

The question

Question: find the volume of a cylinder with radius 3 and height 5.

1 Circle times height

The top is a circle.

Its area is π × r².

The cylinder is that circle, stacked up 5 high.

π is a special number for circles.

It is about 3.14.

So the volume is V = π × r² × h.

Now put the numbers in: r = 3 and h = 5.

3² means 3 times 3.

That is 9.

So V = π × 9 × 5.

9 times 5 is 45.

So V = 45π.

We keep π in the answer.

That is the exact answer.

2 About how much

To see about how much, put 3.14 for π.

45 times 3.14 is 141.3.

So the volume is about 141.3 cubic units.

Let's look back.

First: circle times height.

Last: about how much.