Convert from button measure to decimeter

Unit Definition (button measure)
The button measure is a unit of distance equal to 1/40 inch (0.635 millimeter), used to measure the thickness of buttons.

Unit Definition (decimeter)
The decimeter (or decimetre) a fairly common metric unit of distance equal to 10 centimeters or 3.9370 inches. The decimeter is very close to the hand, a traditional English unit.