Answer: If you measure the circumference and the diameter of a circle and divide the circumference by the diameter, you get the number Pi, which is about 3.14.
Pi is often shown by the Greek letter π .
The ancient Greeks used the symbol π to indicate the ratio between the circumference and diameter of a circle. If your calculator does not have the symbol π , you can use the rounded off number 3.14 for π .
A = 5m × 5m × 3.14 78.5m2 (Note: the symbol means about the same as).
In the diagram above, the area of the small yellow square is a quarter of the area of the big square.
If the area of the shaded square is A = 5m × 5m = 25m2
then the area of the big square is A = 4 × 25m2 =100m2
You can see that the area of the circle is less than that of the square since the circle fits inside it. You can also find the area of the circle by multiplying the area of the small square by Pi:
A = 3.14 × 25m2 =78.5m2