How many inches are in 18 cubic feet?

Answer 1

I'll assume you meant: "how many cubic inches are in 1.8 cubic feet?" since cubic feet are a measure of volume whereas inches are a measure of length:

1 ft = 12 in

⇒ 1 cu ft = 1 ft x 1 ft x 1 ft

= 12 in x 12 in x 12 in

= 1728 cu in

⇒ 1.8 cu ft = 1.8 x 1728 cu in

= 3110.4 cu in

That is 3110.4 cubic inches.

Answer 2

This question cannot be answered sensibly. A cubic foot is a measure of volume, with dimensions [L3]. An inch is a measure of distance, with dimensions [L]. Basic dimensional analysis teaches that you cannot convert between measures with different dimensions such as these without additional information.