### Calculating Percentages

### HOW TO CALCULATE PERCENTAGE CHANGE

**PART AND WHOLE**

A percentage is a way of showing a part out of a whole. The figure 85% means 85 out of 100. Therefore, in order to find percentage change, you'll need two pieces of information: the part (amount of change) and the whole (the original amount).

Let's follow the example of a chess club that began with 8 members and ended up with 14 members. What is the percent change in membership?

**STEP 1: FIND THE AMOUNT OF CHANGE**

Calculate the difference, or the change in values. You can do this by subtracting the smaller number from the larger number.

In this example, you'll end up with 6.

**STEP 2: DIVIDE **

Since a percentage is a part out of a whole, divide the part (the change you just calculated) by the whole.** Always use the original value as the whole** – that's because you're calculating how much this original value changed. In this case, the whole is the original 8 members.

Our figure here is 0.75.

**STEP 3: MULTIPLY**

In order to change this figure to a percentage, simply multiply by 100.

This gives us a solution of 75. Just add a % sign to the end and you are done! The chess club membership changed by 75% and was, more specifically, a 75% increase.

**ANOTHER LOOK**

What would the calculation look like if the chess club had lost members? Suppose they began with 8 members and ended up with 6 members.

Step 1: 8 – 6 = 2

Step 2: 2 ÷ 8 = 0.25

Step 3: 0.25 x 100 = 25

There was a 25% decrease in membership!
Note that values can increase more than 100%. If the price of a movie ticket increases from $5 to $12, that is a 140% increase (it more than doubled). Values do not normally decrease more than 100% because that would bring the value below zero.