When to use it

Use it when a word problem says something like '15 is what percent of 60' to build the proportion before solving.

Example

1560=p100\frac{15}{60} = \frac{p}{100}, so p=25p = 25, meaning 15 is 25% of 60.

Common mistake

Placing the 'of' value in the numerator instead of the denominator. 'Of' always goes on the bottom.