Decimals To Percents
Converting decimals to percents is done by multiplying the decimal by 100, which is equivalent to moving the decimal point two places to the right. The decimal 0.75 becomes 75%, and 0.08 becomes 8%. Conversely, to convert a percent to a decimal, divide by 100 (move the decimal two places left). This Grade 7 math skill from Saxon Math, Course 2 is fundamental for interpreting data in charts and statistics, calculating discounts and interest rates, and understanding any quantitative information expressed as a percentage.
Key Concepts
Property To change a decimal to its percent equivalent, multiply the number by $100\%$.
Examples $ 0.8 \times 100\% = 80\% $ $ 1.5 \times 100\% = 150\% $ $ 0.04 \times 100\% = 4\% $.
Explanation Multiplying a decimal by $100\%$ is like a superpower promotion! It moves the decimal point two places to the right and slaps a percent sign on the end. It's the fastest way to see the 'parts per hundred' value of any decimal, turning it into a grade A superhero of numbers.
Common Questions
How do I convert a decimal to a percent?
Multiply the decimal by 100, or equivalently, move the decimal point two places to the right and add the percent sign. For example, 0.45 becomes 45%, and 0.07 becomes 7%.
How do I convert a percent to a decimal?
Divide by 100, or move the decimal point two places to the left. For example, 38% becomes 0.38, and 6% becomes 0.06.
Why does multiplying by 100 convert a decimal to a percent?
The word 'percent' means 'per hundred.' Multiplying by 100 expresses the decimal as a ratio out of 100, which is the definition of a percent.
What are common decimal-to-percent conversions students should know?
Key equivalents: 0.5 = 50%, 0.25 = 25%, 0.75 = 75%, 0.1 = 10%, 0.01 = 1%, 0.33 = approximately 33%, 0.2 = 20%.
When do students learn to convert decimals to percents?
Decimal-percent conversion is a Grade 6-7 skill. Saxon Math, Course 2 covers it in Chapter 7 as part of the interconnected fraction-decimal-percent system.
What are common mistakes when converting decimals to percents?
Students sometimes add the percent sign without multiplying, giving 0.45% instead of 45%. Always multiply by 100 before adding the % sign.
How does decimal-to-percent conversion help in real life?
Test scores (0.87 = 87%), sales tax rates (0.08 = 8%), and nutritional information (0.35 = 35% of daily value) all use this conversion in everyday reading and calculations.