How to Find a Part of a Whole Number

A percentage can represent a decimal number, and vice versa.

Trying to find part of a whole number can mean either one of two processes: finding the percentage equivalent given a particular portion amount or finding the equivalent decimal amount given a specific percentage. In the former instance, you already know the percentage amount and must calculate the portion amount. In the latter instance, you already know the portion amount and must calculate the percentage.

Things You'll Need

• Calculator

Instructions

When the Percentage Amount is Known

1. Divide the percent amount by 100 to convert the percentage to decimal form. For example: To convert 55 percent to decimal form, calculate 55 / 100 which amounts to .55. Another way to perform this calculation involves moving the decimal point in the original percent amount two places to the left.

2. Multiply the whole number by the decimal equivalent of the percentage. For example: To find 55 percent of 220, calculate .55 x 220. The answer is 121.

3. Write out your final answer. For example: 55 percent of 220 is 121, which answers the question, "How much is 55 percent of 220?"

When the Percentage Amount is Known (Using a Calculator)

1. Enter the percent amount. For example: Enter "55."

2. Press the multiplication button.

3. Enter the whole number amount. For example: Enter "220."

4. Press the percent button to reveal the answer. In the example presented, you'll find that 55 percent of 220 is 121.

When the Percentage Amount is Unknown

1. Write the whole number and portion amount as a fraction with the whole number amount on the bottom of the fraction (functioning as the denominator) and the portion amount on top (functioning as the numerator). For example: If 220 is the whole number and 121 is the portion amount, write 121 / 220.

2. Convert the fraction from Step 1 to decimal form by dividing the numerator by the denominator: For example: 121 divided by 220 equals .55.

3. Multiply the result from Step 2 by 100 to convert the decimal to percent. For example: .55 x 100. The answer is 55 percent. Another way to perform this calculation involves moving the decimal point two places to the right.

4. Write out your final answer. For example: 121 is 55 percent of 220, which answers the question, "121 is what percent of 220?"

References

• Marshu: Percent Calculator and Percentage Formula to Calculate Percent of a Number
• Syracuse University: Review of Percents
• TheMathPage: Percent with a Calculator
• Missouri School Web Project: Percent
• Etymonline: Percent