When to use it

Use it whenever you need the slope of a line on a graph, counting vertical change (rise) divided by horizontal change (run).

Example

A line going from (1,2)(1, 2) to (4,8)(4, 8) has rise =8−2=6= 8 - 2 = 6 and run =4−1=3= 4 - 1 = 3, giving slope =63=2= \frac{6}{3} = 2.

Common mistake

Putting run on top and rise on the bottom. Rise is always the numerator, run is the denominator.