This article looks at percentages when used in the following 4 scenarios:

  1. Finding the % of an amount.
  2. Increasing / decreasing an amount by a %.
  3. Expressing an amount as a % of another amount.
  4. Finding a % increase / decrease.

Finding the % of an amount

Perhaps the most basic question you can be asked on percentages. One way is to convert the precentage value into a decimal then working out the result. Here are some examples

Increase / Decrease an Amount by a %

For this type of questions, you need to add a step 3. This is adding the percentage amount to, or subtracting the percentage amount from, the original amount. Some examples below.

Expressing an amount as a % of another amount

The above two types of % questions are the most common questions used. With this one, things start getting a bit challenging. But worry not, use the technique below.

In the previous examples, we could easily work out the percent value by multiplying the numerator and denominator by a number; but what if we cannot work out the percent value. In this case we must

  1. convert the fraction into a decimal number
  2. multiply the decimal number by 100 to get the percent value

Find the Percentage Increase / Decrease

Finally, this last scenario looks at the case where you are given two values and are asked to find either the percentage increase or decrease.

Numbers - Ratio (Sharing) & 1:n
Numbers - Multipliers