How do you convert feet to decimeters?
Multiply by 3.048. A foot is exactly 0.3048 m, which makes it exactly 3.048 dm.
An 8 ft ceiling comes to 24.384 dm, and 100 feet is 304.8 dm.
For a quick guess multiply by 3, which comes out about 1.6% low. That puts the 8 ft ceiling at 24 dm – close enough to tell whether the wardrobe will fit standing up.
What is a foot?
The foot is an imperial and US unit of length equal to 12 inches, or exactly 30.48 centimeters. It is a third of a yard and 1/5,280 of a mile.
The foot began as the length of a human foot, and so differed from place to place and from person to person. The modern international foot was fixed at exactly 0.3048 meters by agreement in 1959.
People's height is given in feet and inches in the US and UK, and aircraft altitude is given in feet nearly everywhere, metric countries included.
What is a decimeter?
A decimeter (dm) is one tenth of a meter, or 10 centimeters. The 'deci' is the SI prefix for 10^-1.
The decimeter is rarely used by itself, since people go from centimeters straight to meters. You mostly meet it as the cubic decimeter, which is exactly one liter.
A decimeter is about 3.937 inches, so just under four. Divide inches by 3.937 – or multiply by 0.254 – to go the other way.