Fraction Slide Rule

Fraction Slide Rule

 

Adding fractions: To add fraction A and B on the slide ruler.(A + B)

  • Line up ZERO on the top ruler with the fraction "A" on the bottom rule.
  • Find integer "B" on the top ruler.
  • Look at the number below "B" on the bottom rule, you will see the answer of A + B.

Subtracting fractions: To subtract fraction B from A on the slide ruler.(A - B)

  • Find fraction "B" on the top ruler.
  • Find fraction "A" on the bottom ruler.
  • Line top and bottom rulers so that the number being subtracted are one on top of the other.
  • Look on the bottom ruler,  below the ZERO on the top ruler ... and read the fraction on the bottom ruler.   This is the answer to the subtraction problem.

Before the creation of easily available calculators in the late 1960s, people used tools called slide rulers to do addition, subtraction, multiplication and division quickly. This page uses this slide rule concept to help you with fractions.