How to Put Pie R Squared in A Calculator

How to Calculate πr²

The formula for the area of a circle is πr², where π (pi) is approximately 3.14159 and r is the radius of the circle. To calculate πr²:

1. Determine the radius (r) of the circle in the desired units (meters, inches, etc.).
2. Square the radius (r²).
3. Multiply the squared radius by π (3.14159).

Step-by-Step Guide

Using a Basic Calculator

1. Enter the radius value (e.g., 5).
2. Press the "x²" button to square the radius (5² = 25).
3. Multiply the result by π (3.14159 × 25 = 78.53975).

Using a Scientific Calculator

1. Enter the radius value (e.g., 5).
2. Press the "x²" button to square the radius.
3. Press the "×" button, then enter π (3.14159).
4. Press "=" to get the result (78.53975).

Common Mistakes

• Using the diameter instead of the radius: Remember that πr² uses the radius, not the diameter. The diameter is twice the radius.
• Forgetting to square the radius: πr² requires squaring the radius, not just multiplying π by r.
• Using an incorrect value for π: While 3.14 is often sufficient, using more decimal places (3.14159) provides more accuracy.

Real-World Examples

Example 1: Calculating the Area of a Pizza

If a pizza has a radius of 12 inches:

• r² = 12² = 144
• Area = 3.14159 × 144 ≈ 452.389 square inches

Example 2: Calculating the Area of a CD

If a CD has a radius of 3 cm:

• r² = 3² = 9
• Area = 3.14159 × 9 ≈ 28.2743 square centimeters