# How to deduct interest?

Often in life we are confronted with the concept of percentage. If you come to the store, discounts are expressed as a percentage. You are related to the bank: take a loan, put money on a deposit. Yes, and understand the resulting stub on wages. You should always be able to calculate the required percentage. So how to deduct interest? In this article, all tasks for percentages will be considered, including how to subtract a percentage of a number, how to find a number by its percentage, and others. Lightness and availability guaranteed.

## How to deduct a percentage: examples

One percent is one hundredth of the number. To find the percentage of the number you need to make a proportion. For a better understanding, let's consider an example right away: we need to find 15% of the number 225. We take the number 225 as 100%, and the number that needs to be found as X. As a result, we get the proportion: 225/100 = x / 15.

To find the desired number you need to use the rule of proportion, namely the cross product: 225 ∙ 15 = 100 x; x = 225 ∙ 15100 = 33.75

To reduce the record, you can replace the percentages with a number. For this you need to get rid of the% sign, i.e.divide by 100%: 15% / 100% = 0.15. So the same operation can be shortened as follows: 225 ∙ 0.15 = 33.75. Let us fix knowledge on another example: find 24% from 1895: 1895 ∙ 0, 24 = 454.8.

Often there is the question of how to deduct a percentage of the amount - this is also not difficult to solve. Consider an example: Your salary is about 25,000 rubles, you have been deducted tax in the form of 5%. What salary do you get?

First we find 5% of 25,000, then we deduct from the initial amount: 25,000 0.05 = 1250; 25000-1250 = 23,750

Also solved the problem of how to increase the number of a given percentage. Also consider an example: in a skein of cloth was 80 meters, it was increased by 18%. How much has become a meter? A similar problem is solved like this: we find the percentages, and then we add to the initial value: 80 ∙ 0.18 = 14.4 m; 80 + 14.4 = 94.4 m.

On the topic of interest, there is also the question: to determine what percentage is the number of the number. Consider an example: You need to find how many percent is 25 from 200.

To solve such a problem, you need to use the formula: P = x1 / x2 ∙ 100%, where P is what we are looking for, namely the number of percent; x1 is the first number; x2 is the second number. The solution looks like this: 25/200 ∙ 100% = 12.5%.

Consider also the problem of finding the number of its percentage. To solve this problem, it is necessary to make a proportion.For clarity, we consider an example: you need to find a number, 20% of which is 45. We denote a given number by x, then we get the proportion: x / 100 = 45/20; x = 100 ∙ 45/20 = 225.

We will consolidate the material with the help of the following problem: there are 30 students in the class, 60% are girls, and the rest are boys. The question is: how many girls are in a class and how many boys? First we find the percentage: 30 ∙ 0.6 = 18; 30-18 = 12. Answer: in a class, 18 girls and 12 boys.

So we looked at all kinds of interest tasks. It's never too late to learn!