Calculator finds solutions to common percentage problems. It's done in easy way: more like stories and everyday situations, less like math language.

1.1. % is equal to 0.5
| |||

1.2. The number is equal to 19 | |||

1.3. The fraction 75 | |||

1.4. % from the number is 50 |

2.1. The bike was at a price of $. Next, its price has been raised by %. After that, the bike costs 525 $ |

2.2. I'm a regular customer in The Shop and I obtained % discount for future shopping. Regular price of washing machine is $, but I will pay only 800 $ |

2.3. Yeah! There is a promotion this week - it's % discount for all products. Some nice handbag costs $ now. It means, the same handbag was at a price of 58.82 $ (58 $ and 82 cents) |

2.4. The mobile phone costs $ in first shop and $ in another one. It means that, price offered by second shop is 20% higher |

3.1. My usual electricity bill is about $ per month. Unfortunately, the bald man in TV was talking about upcoming increase of electricity price by %. It means I will pay 151.5 $ (151 $ and 50 cents)1.5 $ (1 $ and 50 cents) |

3.2. The landlord increased my rent by $. Before that, I was paying $ to him. This means my rent has grown by 22.22 |

3.3. My monthly gas bill is $ in average. It turned out, that I would pay $ when I switch to another supplier. It will be 20% less |

- One percent (1%) is equal to fraction 1/100 or 0,01:

$1\ percent = 1\% = \frac{1}{100} = 0,01$ - To convert some number into percent, you need to convert it to fraction with 100 denominator first. Then, nominator of fraction will tell you "number of percents".

ⓘ Example: Fraction 3/4 is equal to 75%, because after converting it to denominator 100 we get:

$\frac{3}{4} = \frac{3 \times 25}{4 \times 25} = \frac{75}{100} = 75\%$ - If you need to calculate
**a percent of a number**, you have to multiply that number by a proper fraction with 100 denominator.

ⓘ Example: 50% from number 10 is equal to 5, because:

$50\% \times 10 = \frac{50}{100} \times 10 = \frac{50 \times 10}{100} = \frac{5\cancel{00}}{1\cancel{00}} = 5$ - The concept of percentage is very useful and popular in many areas of our life, for example:
- Income from bank deposit is usually defined as percent of capital, that you would earn after one year. It's so called
**annual rate of return**.

- Change in a value is often expressed as percentage of inital value. For example: the handbag is 20% cheaper than it was before the summer discount.

- Concentration of one substance in another is often expressed in percentage values (percentage concentration). For example you can buy 3% solution of hydrogen peroxide (H
_{2}O_{2}) to desinfect wounds. It means that in 100g of solution you'll get 3g of the active substance (i.e. hydrogen peroxide).

- Income from bank deposit is usually defined as percent of capital, that you would earn after one year. It's so called

- Use
**percentage commutativity**and surprise your friends!

- ⓘ Example: Let's calculate 18% from 50 in memory. Looks difficult? Don't worry - there is nothing easier. Let's swap number and percentage and we get 50% from 18. 50% of something is same as half of something ! So, we need half of 18, which is 9.

$18\% \times 50 = 50\% \times 18\% = \frac{1}{2} \times 18 = 9$ - Why does it work? Percentage commutativity is related to multiplication commutativity. Because calculating percentage from given number is the same as multiplying this number by fraction (x/100), this operation is commutative too.

- ⓘ Hint: Remember and impress friends:
**X% from number Y is the same as Y% from number X**.

$X\% \times Y = Y\% \times X$

- First of all, find the sentence in calculator, which describes your problem in the closest way. However, don't take those sentences too literally ! Those sentences describe example situations - like buying handbag under promotion. However, you can enter any other product in this place. Be creative, don't waste your imagination.

- Next, click on one of input fields in the sentence and enter your own value.

- After you've entered the numbers in the particular sentence, the other part of a sentence will adjust automatically, displaying the correct number as a solution.

- Remember - if you can't find a sentence describing your situation, feel free to drop us a word. We will be happy to add the missing case for you!

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"Calculla v1" version of this calculatorIn December 2016 the Calculla website has been republished using new technologies and all calculators have been rewritten. Old version of the Calculla is still available through this link: v1.calculla.com. We left the version 1 of Calculla untouched for archival purposes.

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