Economists and technicians often have to calculate the number of interest. Accountants need to correctly calculate the taxes to bankers – revenue (interest) on deposits, the engineers of the tolerance parameters. In all such cases it is necessary to consider the interest from some known values.

### You will need

- a calculator or computer.

### Manual

**1.** To calculate the percentage of a number, the number must be multiplied by the number of percentages, and then divide by 100. For example, if the employee’s salary amounted to 30,000 rubles, income tax (13%) of this amount will be: 30000 * 13 / 100 = 3900 rubles.

**2.** To calculate the percentage of a number on a regular calculator, perform the following sequence of actions. Type the number of percent («button%» while pushing). Click on any of the signs of arithmetic operations («+», «-«, «x», «/», in this case this button is used as the delimiter when you enter numbers). Now type on the calculator the number from which you want to calculate the interest. Click on the «%». The indicator of the calculator will display the desired result.

**3.** To calculate the number of interest and using the computer. To do this, start the standard Windows calculator. To do this, click start — > Run -> type «calc» -> OK. If the calculator is loaded into «Engineering» form, install it in «Normal» mode («View» -> «Normal»). Then count the percentage number, as described in the previous paragraph instructions.

**4.** To calculate the number of interest in MS Excel, type the following sequence of characters: «= » «» » * » «percent» «Enter». So, for example, to calculate 13% of 10000, enter in the desired cell the following formula: =10000*13% and press «Enter». If you did everything correctly, then in the cell instead of the formula you will see the number 1300.