How to calculate the area of a square or rectangle

If you forgot how to calculate the area of a rectangle from way back in geometry class, here's how.

Things You'll Need

• possibly a measuring tool such as a ruler
• possibly a calculator

Instructions

1. 

   First measure the sides of the rectangle or square. If you're looking at a marked diagram or blueprint, it will probably appear with measurements such as in the attached image. If the unit is inches, it would be 3 inches tall by 7 inches wide.

2. Once you have the measurements, multiply the measurements of the two different sides by each other. So in the above case, it would be 3 times 7 which equals 21, which is the area.

3. Now that you have the area, it should be expressed in square units. So if it's 21 inches, it should be written as "21 square inches."