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Percents
Percent is a hundredth part of unit. A record 1% means 0.01. There are three main problems by percents:

Problem 1. Find an indicated percent of a given number. The given number is multiplied by the indicated number of percents; then a product is divided by 100.

Example: A deposit in a bank has an annual increase 6%. A sum of money in the beginning was equal to \$10000. How many dollars will the sum be increased by in the end of the year?

Solution: \$10000 · 6 : 100 = \$600.

Problem 2. Find a number by another given number and its percent value of the unknown number. The given number is divided by its percent value; the result is multiplied by 100.

Example: A salary by January was equal to \$15000, that was equal 7.5% of an annual salary. What was the annual salary ?

Solution: \$15000 : 7.5 · 100 = \$200000 .

Problem 3. Find the percent expression of one number by another. The first number is divided by the second, and a result is multiplied by 100.

Example: On 2001 a plant have produced 40000 cars; and on 2002 - only 36000 cars. What percent does it constitute relatively to the output of 2001 ?

Solution: 36000 : 40000 · 100 = 90% .
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