How do you find the area of a rectangle with length 8 and width 5?

To find the area of a rectangle, you multiply the length by the width. The area represents the amount of space inside the rectangle, and this is calculated using the formula:

Area = Length × Width

In this case, the length of the rectangle is 8 units, and the width is 5 units. By applying the formula, you calculate the area as follows:

Area = 8 × 5 = 40 square units.

This method is fundamental in geometry, and understanding it helps with solving various problems related to shapes and their dimensions. Other options like adding or subtracting the length and width do not yield the area of a rectangle, as they do not account for the space that the shape covers. Therefore, multiplying length and width is the correct operation to determine the area.