Converting to a percent
Convert decimals and fractions to percentages: multiply by 100 and add the percent sign to enable comparisons of proportional quantities in consumer math and data problems.
Key Concepts
To write a decimal as a percent, multiply the decimal by 100. To write a fraction as a percent, first convert it to a decimal by dividing the numerator by the denominator, then multiply by 100.
To convert $0.045$ to a percent: $0.045 \times 100 = 4.5\%$. To convert $\frac{3}{8}$ to a percent: $3 \div 8 = 0.375$, so $0.375 \times 100 = 37.5\%$. To convert $5$ to a percent: $5 \times 100 = 500\%$.
Turning a number into a percent is like giving it a "per 100" makeover. "Percent" literally means "per hundred," so we just multiply by 100 to see how many parts out of a hundred it represents. For fractions, we just do the division first to get a decimal, then it is a simple hop to percent land!
Common Questions
How do you convert a decimal to a percent?
Multiply the decimal by 100 and append the percent sign. For example 0.75 times 100 = 75%. Conceptually, percent means per hundred, so multiplying by 100 scales the decimal to show how many parts per 100 the value represents.
How do you convert a fraction to a percent?
First divide the numerator by the denominator to get a decimal, then multiply by 100. For example 3/8 = 0.375, and 0.375 times 100 = 37.5%. Alternatively, find an equivalent fraction with denominator 100.
How are percent conversions used in consumer math applications?
Percent conversions appear in interest rate calculations (converting 5% to 0.05 before using I=Prt), discount problems (subtracting 20% means multiplying by 0.80), and tax calculations (adding 8.5% means multiplying by 1.085). Converting between forms is the first step in most financial algebra problems.