Question

A circular pool has a radius of 20 feet. What is the area of the pool? Use 3.14 for π.

Answer 1

The formula for area is
$\pi {r}^{2}$
However, we are substituting pi for 3.14, so in this case the formula is 3.14×r^2
Here's a non-calculator method:
When r=20, A=3.14×20^2
20^2=400
Let's convert 3.14 into an integer by multiplying by 100, so we can deal with the numbers more easily:
314×400=(314×400)×100=125600
Now divide by 100 to put the decimal places of 3.14 back:
125600÷100=1256
If you noticed, we could have just cancelled out the decimal places in the 3.14 by dividing 400 by 100, meaning we could have just done 314×4
Besides this, the area of the pool is 1256ft^2

Answer 2

Since you already know the radius multiply it by itself(20*20=400)then multiply that amount by 3.14.(formula: 3.14*(radius*radius)