Step by step
The question
Question: find the volume of a cylinder with radius 4 and height 6.
1 Circle times height
The top is a circle.
Its area is π × r².
The cylinder is that circle, stacked up 6 high.
π is a special number for circles.
It is about 3.14.
So the volume is V = π × r² × h.
V = π × r2 × h
Now put the numbers in: r = 4 and h = 6.
V = π × 42 × 6
4² means 4 times 4.
That is 16.
42 = 4 × 4 = 16
So V = π × 16 × 6.
V = π × 16 × 6
16 times 6 is 96.
So V = 96π.
We keep π in the answer.
That is the exact answer.
V = 96π
2 About how much
To see about how much, put 3.14 for π.
V ≈ 96 × 3.14
96 times 3.14 is 301.44.
So the volume is about 301.44 cubic units.
V ≈ 301.44
Let's look back.
First: circle times height.
Last: about how much.
Answer
V ≈ 301.44