1. Convert the fraction to a decimal:
* One eighth is equal to 1/8 = 0.125
2. Add the whole number:
* 1 + 0.125 = 1.125 inches
3. Convert inches to millimeters:
* 1 inch is equal to 25.4 millimeters
* 1.125 inches * 25.4 mm/inch = 28.575 mm
Therefore, 1 and one eighth inches is equal to 28.575 millimeters.
