Convert 3 feet long by 18 inches wide into cubic feet?

Answer 1

Before a calculation of this sort, the measurements must both be in the same unit.... as inches cannot be multiplied by feet to give a meaningful result.

So, as square feet are being sought, convert the 18 inches to feet. This gives a figure of 1.5 feet.

Now we can do the calculation for area - multiply the length by the width.

3 x 1.5 = 4.5

This is square feet, so the answer is 4.5 square feet.