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# Decimals & Percent: sub-module 2 of 4 of math tutorials When you pay sales tax, determine how much an item costs on sale, or calculate your final mark in a course, you are applying concepts of percentages. A percent is a fraction with a denominator of 100. To show that a number is a percent, we use the percent symbol (%) beside the number. This module will help you understand what a percent is, how to convert between a percent, fraction, and decimal, and how to solve sales tax, commission, discount, and percent change problems. This module also covers place value and rounding in decimals.

## Top Tips

• To convert a percent to a decimal, move the decimal point to the left. To convert a percent to a decimal, move the decimal point two spots to the left and remove the percent symbol (e.g. 3% as a decimal is 0.03).
• To convert a decimal to a percent, move the decimal point to the right. To convert a decimal to a percent, move the decimal point two spots to the right and add the percent symbol (e.g 0.15 as percent is 15%).
• When doing calculations with a percent, convert the percent to a decimal first. Once you have a decimal, you can do your calculations with that.
• To convert a percent to a fraction, write it with a denominator of 100. Percentages are essentially fractions with a denominator of 100. Write the number of the percent on top and 100 on the bottom, and then simplify the fraction.
• To convert a fraction to a percent, first convert to a decimal. Once you have your decimal number, you can convert that into a percent.
• To solve percent application problems, look for your knowns and unknowns. First determine what the question is asking you to find, and choose a variable to represent what you are being asked to find. Use this information to translate the word problem into an equation that you can solve to get the answer.