# Percents

*Percent. Three main problems by 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. |

E x a m p l e . | 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? |

S o l u t i o n : $10000 · 6 : 100 = $600.

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

E x a m p l e . | A salary by January was equal to $15000, that was equal 7.5% of an annual salary. What was the annual salary ? |

S o l u t i o n : $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. |

E x a m p l e . | 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 ? |

S o l u t i o n : 36000 : 40000 · 100 = 90% .

### Related post:

- Ratio and proportion. Proportionality
- Converting a decimal to a vulgar fraction and back
- Operations with decimal fractions
- Decimal fractions (decimals)
- Operations with vulgar fractions
- Vulgar (simple) fractions
- Least common multiple
- Greatest common factor
- Factorization. Resolution into prime factors
- Divisibility criteria