Many precise measurements are given in decimal form. Although decimal form is very precise, it can be difficult to translate the form to a reallife application. Fortunately, it is possible to convert decimals to fractional ruler measurements with a little bit of math. It is important to realize that the conversions will not be completely accurate. They will be rounded to the nearest 1/32 of an inch, or whichever increment is chosen.

Take the decimal and subtract the whole number from it. The whole number will be the number of full inches. For example, 3.456 inches minus 3 inches is .456 inches

Take the remaining portion of the decimal and multiply it by the fraction increment desired. For example, if your ruler measures to the nearest 1/32nd of an inch, multiply the decimal portion by 32. In this example, .456 times 32 equals 14.592.

Round the value from step 2 to the nearest whole number. For this example, 14.592 rounds up to 15. This value is the numerator of the fractional inch over 32.

Add the whole number from step 1 to the fraction in step 3. For example, 3 plus 15/32 equals 3 and 15/32 inches.
References
 "Measurements & Conversions"; Pamela Liflander; 2003
 El Paso Community College: Converting Fractions, Decimals, and Percents