Calculating Percentage Review

​A Percent is a part of a whole, much like a decimal or a fraction. Example..... 97% means 97 out of 100.

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​A percent will always be out of 100

​9 out of 10 = 90% It is equal to 90 out of 100

Any number can be a percentage of another number. ​Using multiplication and division we can figure a percent from the numbers given. The word "percent" means per hundred!

​I scored 17 out of 20 on a test.

​To find my percentage grade, divide 17 by 20.

You'll get 0.85. We need to move the decimal to the right two places to make that a percentage. My score was 85%. That is equal to scoring 85 out of 100 on a test. The correct term is equivalent ratios. ​

​Remember to turn a percentage to a decimal you simply move the decimal over to the right or the left two spaces.

​The word "percent" means per hundred!

Multiply the decimal by the number. That's your answer.

​The word "of" means multiply

​87% would be 0.87

5% would be 0.05

10% would be 0.10​

92% would be 0.92​

​Turn the percent into a decimal

​Finding a percent of a number:

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​40% equates to 0.40

The word "of" means multiply

0.40 X $42.99 = $17.19

Because we're working with money we go to the hundredths place​

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​Find 40% of $42.99

20% equates to 0.20​

​The word "of" means multiply. 0.20 X 94 = 18.8

​Find 20% of 94

​Let's try a few!

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​Some problems have multiple steps

Many word problems want you to find a percentage and then calculate a new value using that answer. Think about putting money into a bank account that grows interest or shopping for an item of clothing that is on sale. Another example is calculating weight or height if you consider growth. ​

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​I put $50 in the bank a few years ago. It grew by 20%. How much money do I have now?

We first have to turn 20% back into a decimal. Drop the percentage sign and move the decimal from the end to the left two spaces. That gives us 0.20. Now multiply 0.20 by 50. You get 10. Add that to the original $50 and you see I now have $60.​

What is 12% of 9? 12% equates to 0.12 and the word "of" means multiply.

0.12 X 9 = 1.08 pounds. Now we need to add that to our original weight. ​

9 + 1.08 = 10.08 pounds which would be his current weight. ​

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​This dog's weight used to be 9 pounds. His weight has increased by 12%. How much does he weigh now?

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15% equates to 0.15 and we find the percentage amount using multiplication. ​0.15 X 35 = 5.25

5.25 is how much she has gained. To find out how much she used to weigh we now subtract 5.25 from 35 and we see she used to weigh 29.75 pounds. ​

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​This cat's weight has increased by 15%. She now weighs 35 pounds. How much did she used to weigh?

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Percents!!!!

​The word percent means "per 100"

To turn a percent into a decimal, we always move the decimal point to the left two spaces.

In a word problem, the word OF means to multiply.