Convert from digit to micron

Unit Definition (digit)
The digit is a historic unit of distance equal to the width of a person's finger. Used in all the ancient civilizations of the Middle East and Mediterranean, the digit was equal to 0.75 inch or 19 millimeters with only the smallest variations. Typically, there were 4 digits in a palm, 16 in a foot, and 24 (sometimes 28) in a cubit. The word digit is from the Latin word for a finger or toe, digitus.

Unit Definition (micron)
A unit of length. One Micron = 39 millionths of an inch (.000039"). Contaminant size is usually described in microns. Relatively speaking, a grain of salt is about 60 microns and the eye can see particles to about 40 microns. Many hydraulic filters are required to be efficient in capturing a substantial percentage of contaminant particles as small as 5 microns. A micron is also known as a micrometre, and exhibited as µm.