Area of Rectangles by Tiling

A unit square is a square having each side of length 1 unit. The area of a unit square is 1 square unit.

For example, consider the following rectangle made of unit squares.

1 a

Let's find the area of this rectangle.

To find out the area, we need to count the total number of unit squares.

 

1 b

 

There are 15 unit squares inside the rectangle.
 

So, the area of the given rectangle is 15 square units.