How to find percentage of a number? Interest calculator online. how to find the percentage of a number how to get the percentage of a number

A percentage is one hundredth of a number taken as a whole. Percentages are used to indicate the ratio of a part to a whole, as well as to compare quantities.

1% = 1 100 = 0,01

The interest calculator allows you to perform the following operations:

Find percentage of a number

To find a percentage p from a number, you need to multiply this number by a fraction p 100

Let's find 12% of the number 300:
300 12 100 = 300 0.12 = 36
12% of 300 equals 36.

For example, a product costs 500 rubles and a 7% discount applies to it. Find the absolute value of the discount:
500 · 7 100 = 500 0.07 = 35
Thus, the discount is 35 rubles.

What percentage is one number of another

To calculate the percentage of numbers, you need to divide one number by another and multiply by 100%.

Let's calculate how many percent is the number 12 of the number 30:
12 30 100 = 0.4 100 = 40%
The number 12 is 40% of the number 30.

For example, a book contains 340 pages. Vasya read 200 pages. Let's calculate how many percent of the whole book Vasya has read.
200 340 100% = 0.59 100 = 59%
Thus, Vasya read 59% of the entire book.

Add a percentage to a number

To add to the number p percent, you need to multiply this number by (1 + p 100)

Let's add 30% to the number 200:
200 (1+ 30 100 ) = 200 1.3 = 260
200 + 30% equals 260.

For example, a subscription to the pool costs 1000 rubles. From next month they promised to raise the price by 20%. Let's calculate how much the subscription will cost.
1000 (1+ 20 100 ) = 1000 1.2 = 1200
Thus, the subscription will cost 1200 rubles.

Subtract a percentage from a number

To subtract from the number p percent, you need to multiply this number by (1 - p 100)

Subtract 30% from the number 200:
200 (1 - 30 100 ) = 200 0.7 = 140
200 - 30% equals 140.

For example, a bicycle costs 30,000 rubles. The store gave him a 5% discount. Let's calculate how much the bike will cost, taking into account the discount.
30000 (1 - 5 100 ) = 30000 0.95 = 28500
Thus, the bike will cost 28,500 rubles.

By what percentage is one number greater than the other?

To calculate how many percent one number is greater than another, you need to divide the first number by the second, multiply the result by 100 and subtract 100.

Let's calculate how many percent the number 20 is greater than the number 5:
20 5 100 - 100 = 4 100 - 100 = 400 - 100 = 300%
The number 20 is greater than the number 5 by 300%.

For example, the salary of a boss is 50,000 rubles, and an employee is 30,000 rubles. Find by how many percent the boss's salary is higher:
50000 35000 100 - 100 = 1.43 * 100 - 100 = 143 - 100 = 43%
Thus, the boss's salary is 43% higher than the employee's salary.

By what percentage is one number less than the other?

To calculate how many percent one number is less than another, you need to subtract from 100 the ratio of the first number to the second, multiplied by 100.

Let's calculate how many percent the number 5 is less than the number 20:
100 - 5 20 100 = 100 - 0.25 100 = 100 - 25 = 75%
The number 5 is less than the number 20 by 75%.

For example, freelancer Oleg in January completed orders for 40,000 rubles, and in February for 30,000 rubles. Let's find by what percentage Oleg earned less in February than in January:
100 - 30000 40000 100 = 100 - 0.75 * 100 = 100 - 75 = 25%
Thus, in February Oleg earned 25% less than in January.

Find 100 percent

If number x it p percent, then you can find 100 percent by multiplying the number x on the 100p

Finding 100% if 25% is 7:
7 · 100 25 = 7 4 = 28
If 25% equals 7, then 100% equals 28.

For example, Katya copies photos from her camera to her computer. 20% of photos were copied in 5 minutes. Let's find how much time the copying process takes:
5 · 100 20 = 5 5 = 25
We get that the process of copying all the photos takes 25 minutes.

The percentage shows the hundredth of the unit, which is indicated by the "%" sign. This indicator is used to indicate the proportion of something to the whole. How to calculate a percentage of a number was still known in ancient Rome. Before the decimal system was invented, calculations were made using fractions that were a multiple of 1 to 100. Octavian Augustus took a tax of one hundredth on goods that were sold at auction, and was called Centesima Rerum Venalium. Calculations using multipliers are somewhat similar to calculating percentages.

With the replacement of currency in the Middle Ages, calculations with a denominator of one hundred became more common, and from the end of the 16th century to the beginning of the 17th century, this method of calculation began to be used by everyone, based on materials that contain arithmetic calculations. According to the materials, this method was used in calculating profit and loss, interest rate, as well as the rule of three. In the seventeenth century, this form of calculation was the standard for formulating interest rates in hundredths. The concept of interest in Russia was introduced by Peter I. However, it is believed that similar calculations began to be used in the Time of Troubles, as a result of the first binding of minted coins 1 to 100, when the ruble cost 10 hryvnias, and a little later - 100 kopecks.

Sometimes two quantities are compared without comparing their values, but as a percentage. For example, the price of two goods is not compared in terms of money, but compared as a percentage of how much the price of one product exceeds the price of the other. If it is possible to determine how much one indicator is greater or less than another, then for comparison in%, it is necessary to indicate in relation to which value the percentage is calculated. Such an indication is sometimes not necessary, in the case when it is said that one indicator is greater than the other by a number of percent that is greater than the indicator 100. In this case, there is one way to find the percentage, divide the difference by the smaller of the two numbers and multiply this number by 100.

How to find percentage of a number

In order to find a percentage of a number, you need to multiply this number by the number of percent and divide the resulting number by one hundred. As a rule, there are three main types of problems for calculating interest:

• Calculate the percentage of the given number. This number must be multiplied by the specified percentage, and then the result must be divided by 100.
• Determine the number given by another number and its value as a percentage of the desired number. This number must be divided by a percentage and the result multiplied by 100.
• Determine the expression of one number from another as a percentage. Divide the first number by the second and multiply the result by 100.

As a rule, in an economy where most indicators are expressed as percentages, the change in such indicators is expressed not in% of the original indicator, but in percentage points, which show the difference between the new and old values ​​​​of the indicator. For example, if the business activity index in a country increased from 50% to 51%, then its changes are calculated in the following way: (51% -50%)/50= 1/50=2%, which is 1% in percentage points.

Knowing how to find percentages is necessary for every person. Life gives us tasks to find percentages all the time and, sometimes, several times a day. This is the percentage of the discount in the store, and the interest on the bank deposit, and much more.

Before you understand how to find percentages, you need to define this mathematical concept. So, one hundredth of any number is called a percentage.

How to find percentage of a number

Suppose we need to solve the problem: “A 5% discount is announced in the store. How many rubles cheaper is the skirt now, the original price of which was 300 rubles? To solve this problem, we need to calculate how many rubles will be 5% of 300 rubles, i.e. find the percentage of a number.

As we have already said, a percentage is a hundredth of any number. Then we calculate how much it will be 1% of 300 rubles. To do this, we divide 300 by one hundred. It turns out that 1% of 300 is 3.

Now that we know what 1% is equal to, we can easily calculate how many rubles will be 5% of 300 rubles. You just need to simply perform the following action: 3 * 5 = 15 (rubles).

Thus, the skirt became cheaper by 15 rubles.

It's even easier to find a percentage of a number using a proportion.

300 rubles - 100%

X rubles - 5%

Hence X \u003d (300 * 5) / 100 \u003d 15 rubles.

How to find the percentage of the amount

Finding the percentage of the amount is very easy. First, add up all the terms. Then the resulting amount is divided by one hundred, and the result is multiplied by the number of percent, which is specified by the conditions of the problem.

For example, you want to find 7% of the sum of the numbers 35 and 42.

1. 35 + 42 = 77
2. 77: 100 = 0,77
3. 0,77 *7 = 5,39

How to find percentages with a calculator

It is easiest to understand and remember how to find percentages using a calculator using a specific example. To do this, let's find 9% of 749.

On the calculator, multiply the number from which we find the percentage by the number of percent and click the "%" icon. Please note that when finding percentages on the calculator, you do not need to press the “=” key.

How it looks in our example: 749 * 9%. If everything is typed correctly, then the number “67.41” will appear on the screen, which is the answer to this problem.

We were often told in school that mathematics would be useful to us in life. Partly it is. Integrals and limits are not useful to us in life, but we have to count money every day. Most often, the concept of interest appears in monetary transactions. Today we are with you and we will learn to find them.

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What is interest?

This word comes from the English phrase Pro Centum. After reading this phrase, you probably noticed that the word cent is present there. This is where the meaning of interest comes from. As you know, a cent is one hundredth of a dollar. Therefore, 1% is one hundredth of the number.

Now many financial indicators are measured in percentages:

1. taxes;
2. shares in the business;
3. return on investment;
4. bonuses and penalties;
5. inflation.

And not only financial:

1. fertility and mortality;
2. statistics of successful and unsuccessful marriages;
3. efficiency.

Let's take a closer look at how to calculate the percentage of the amount. We will give you some examples to help you understand.

Example 1. The taxi driver worked his shift. During the day, his revenue amounted to 5 thousand rubles. He needs to give the taxi service a commission from these orders - 15%. To find out the amount that the driver must pay, you need to multiply 5 thousand by 15, and then divide by 100. We get a result equal to 750 rubles. As you may have guessed, 15% is 15 parts out of a hundred.

Now we will give you a reverse example with the same taxi driver. So, for the shift he earned 5 thousand rubles. He spent a certain part of this money on obligatory expenses:

1. taxi service commission - 750 rubles;
2. car wash - 250 rubles;
3. fuel - 1 thousand rubles.

In total, the driver has 3 thousand rubles left. Of the 5 thousand rubles earned, he takes only 3 for himself. Now our task is to calculate what part of the total revenue he can safely put in his pocket. To do this, we need to divide 3 thousand by 5 thousand. After that, the result, equal to 0.6, is multiplied by 100%. It turns out that the driver takes 60% of the total revenue into his pocket.

Example 2. Four shareholders have opened a business. After a year of hard work, he began to generate income. The partners decided to share the profits equally, that is, each will get 25% of the profits. We need to calculate how much money each of them will receive.

Let's say a business generates income of 200 thousand rubles a month. To calculate the profit of each of the shareholders, it is necessary to multiply 200 thousand by 25, and divide by 100. We get the result - 50 thousand rubles.

Example 3. Sales conversion. A sales manager offers his company's services over the phone. He made 800 calls in a month. 280 clients became interested in the company's services. To calculate the sales conversion, you need to divide 280 by 800, then multiply by 100. The result will be 35%.

Percentage Tricks

1. a field for entering a percentage;
2. a field for entering a number, the percentage of which we will find;
3. "Calculate" button.

You can easily find such a calculator on the Internet, you do not have to bother with calculations. In principle, it is logical to enjoy all the benefits of the Internet. However, in life there are situations when it is necessary to calculate the percentage of a number, but there is no calculator at hand.

You can find online calculators on the following websites:

1. calculator888.ru;
2. fin-calc.org.ua;
3. calc.by.

If you need to find 20% or 40%, multiply the sum by 0.2 and 0.4 respectively.

A very simple technique for finding percentages - division. But it can only be used with numbers that are easily divisible by 100. For example, 100 is easily divisible by 25. The result of division is four. This means that to find 25% of the amount you just need to divide it by 4. Using the same scheme, you can find 10, 20 and 50% of the amount you need.

Knowing how to calculate interest on interest will help you plan your income. For example, with a deposit with an interest rate of 10% per year, your income for 2 years will be 21%. Because in the second year, interest was already accrued on the amount accumulated during the first year. And this is 110% of the amount of the down payment.

Conclusion

In conclusion, I would like to say that knowing how to calculate the percentage of a number, help you in life. After all, they will not be able to deceive you when selling goods and when issuing wages. You are given a certain percentage of the money that you have earned. Feel free to ask your boss for pay slips. Carefully check and recalculate all payment documents, because you can be deceived. As the saying goes: "Trust, but verify!".

In this short video tutorial, we will learn how to solve percentage problems using a special formula, which is called the simple interest formula. Let's put this formula in the form of a theorem.

The simple interest theorem. Let's assume that there is some initial value x , which then changes by k%, and a new value y is obtained. Then all three numbers are related by the formula:

Plus or minus in front of the coefficient k is placed depending on the condition of the problem. If, by the condition, x is increasing, then k is preceded by a plus. If the value decreases, then the coefficient k is preceded by a minus.

Despite the apparent sophistication of this formula, many tasks can be solved very quickly and beautifully with its help. Let's try.

Task. The price of the goods was increased by 10% and amounted to 2970 rubles. How much was the product worth before the price increase?

To solve this problem using the simple interest formula, we need three numbers: the original value x , the percentage k and the final value y . Of all three numbers, we know the percentages k = 10 and the final value y = 2970. Please note: 2970 is exactly the final price, i.e. y . Because according to the condition of the problem, the initial price for the goods is unknown (it just needs to be found). But then it was increased, and only then amounted to 2970 rubles.

So we need to find x , i.e. original value. Well, we substitute our numbers into the formula and get:

We add the numbers in the numerator and get:

We reduce one zero in the numerator and denominator, and then multiply both sides of the equation by 10. We get:

11x = 29700

To find x from this simple linear equation, you divide both sides by 11:

x = 29700: 11 = 2700

As you can see, these are quite large numbers, so such calculations cannot be done in the mind. If you meet such a task at the exam, you will have to share a corner. In this case, everything was divided without a trace, and we got the value x :

x=2700

That's what it was worth before the price increase. And it was this number that we needed to find according to the condition of the problem. So that's it: problem solved. Moreover, it was not solved "blank", but with the help of a simple percentage formula - quickly, beautifully and clearly.

Of course, this problem could be solved in a different way. For example, through proportions. Or an exotic method of coefficients. But it will be much better and more reliable if you are armed with several tricks for solving any problem with interest. So be sure to practice using this formula.

And that's all for me. Pavel Berdov was with you. See you soon! :)