Convert 100 feet to inches

100' = 1,200″

A foot is exactly twelve inches, so multiply the feet by 12 and add any leftover inches: 100 feet = 1,200 inches.

Divide by 12: the whole part is the number of feet and the remainder is the inches. That turns 1,200 inches back into 100 feet.

Yes, and it has been since the 1959 international agreement that also fixed the foot at 0.3048 m. Because the ratio is a whole number, 100 feet equals 1,200 inches with nothing rounded away.