# Pre-Algebra Examples

Step 1

The circumference of a circle is equal to Pi times the diameter .

Step 2

Since the diameter is equal to times the radius , the formula for circumference using radius is .

Step 3

Substitute the value of the radius into the formula for the area of a circle. Pi is approximately equal to .

Step 4

Multiply by .

Step 5

The result can be shown in multiple forms.

Exact Form:

Decimal Form: