A square foot of wall needs 1/8 quart of paint.

To calculate the amount of paint needed for a wall, first determine the area of the wall in square feet. Then, multiply the area by the paint requirement per square foot.

Let's assume the area of the wall is 120 square feet. To calculate the amount of paint needed, we multiply the area by the paint requirement:
120 square feet * 1/8 quart per square foot = 120/8 = 15 quarts of paint.