Convert Percents to Decimals
Converting percents to decimals involves moving the decimal point two places to the left because percent means per hundred or hundredths. For example, 45% becomes 0.45, 150% becomes 1.5, and 8.5% becomes 0.085. This skill is covered in Chapter 5 of Saxon Math Course 2 for 7th grade math. Converting between percents and decimals is essential for calculating discounts, tax, tips, and interest rates, making it one of the most practical math skills students will use in everyday life.
Key Concepts
Property Recall that percent means 'per hundred' or 'hundredths.' A percent may be written as a decimal using the same digits but with the decimal point shifted two places to the left.
Examples $45\% = 0.45$ $150\% = 1.5$ $8.5\% = 0.085$.
Explanation Converting percents to decimals is like a magic trick! Since 'percent' means 'out of 100,' you just take the number and move the decimal point two places to the left. If there is no decimal point, imagine it is hiding at the very end of the number before you move it. Poof! Your percent is now a decimal.
Common Questions
How do you convert a percent to a decimal?
Move the decimal point two places to the left and remove the percent sign. For example, 45% becomes 0.45, and 8.5% becomes 0.085. If the percent is a whole number like 7%, think of it as 07.0% and shift to get 0.07.
Why do you move the decimal two places to convert percent to decimal?
Because percent literally means per hundred. Dividing by 100 is the same as moving the decimal point two places left. So 45% = 45/100 = 0.45.
Can a percent be greater than 100 as a decimal?
Yes. Any percent greater than 100 converts to a decimal greater than 1. For example, 150% = 1.5 and 250% = 2.5. This represents more than one whole.
What is 8.5% as a decimal?
8.5% as a decimal is 0.085. Move the decimal point two places to the left: 8.5 becomes 0.085. This is a common conversion in sales tax and interest rate problems.
When do students learn to convert percents to decimals?
Students typically learn this in 6th or 7th grade math. Saxon Math Course 2 covers percent-to-decimal conversion in Chapter 5, building toward more complex percent applications like tax and discount calculations.
What are common mistakes when converting percents to decimals?
The most common mistake is moving the decimal the wrong number of places. Students sometimes write 45% as 4.5 instead of 0.45. Another error is forgetting to move the decimal for single-digit percents like 5%, which should be 0.05, not 0.5.