Advice 1: How to subtract a percentage of the amount

Often in life we have to use simple mathematical operations quickly and without the aid of electronic calculators. For example, the calculation of wages should be deducted from the total monetary amount of thirteen percent. How to do it? After subtracting different types of numbers can not, without a certain conformity between them. And it can be done, knowing a number of simple actions.
How to subtract a percentage of the amount
Instruction
1
For starters, the number, expressed as a percentage, translates into the same meaning that it has a total deductible amount. This is solved the proportion: the sum total is one hundred percent, but an unknown amount is the percentage. "Unknown amount" is the translated value, which will need to deduct from the total amount. If you write the members of the proportion below each other, respectively, it is easy to understand the principle of its decision: "criss cross". That is, the cross lying known members are multiplied and the product divided by the member, not having a pair. Example. May need to calculate a deduction of thirty-five percent of the amount of income equal to one hundred and fifty rubles. Is made proportion: 150 rubles - 100% of "x" rubles – 35 %. "X" rubles = (150 rubles*35%)/100%=52.5 ruble.
2
After finding the deducted value deducted from the total amount found expression. The difference is the solution of the problem. Example. Of the total income equal to one hundred fifty rubles to take thirty five percent, constituting fifty-two and a half rubles. It turns out, 150-52,5=97.5 rubles.

Advice 2: How to subtract percentages

A percentage of a number is a hundredth of this number, denoted by 1%. One hundred percent (100%) equal to the number, and 10% of the number equal to a tenth of that number. Under the subtraction percent decrease understand the numbers on what the share.
How to subtract percentages
You will need
  • Calculator, paper, pen, skills of oral accounts.
Instruction
1
Turn on the calculator and enter a number N from which you want to deduct a percentage.
2
Press the " - " sign, then dial M percentage you want to subtract and press "%", then press "=". As a result, you will receive a number that is less than the number N by M percent.
3
If you don't have a calculator, divide the number N by 100. So you will receive the part number, which is 1 per cent. Next, the resulting, after dividing, multiply by the number M. as a result, you will receive a part of the number K, which accounts for M%. Then subtract from the initial number N number K, which is equal to M percent of the number N. the result of subtraction, you will receive a number that is less than N by M percent. That is, you deduct from the number a fraction of a percent.
Note
The percentage deducted may not exceed the value of 100. The interest rates vary from zero to one hundred.
Useful advice
The same way you can to a number and to add interest. To do this, instead of the key with the sign "-", press the "+"sign.

Advice 3: How to determine the percentage of the amount

The tasks for the interest you have to face not only the students. As a rule, in school assignments, we either need to find a numerical expression of a certain amount percent, or what percentage of something a number. To successfully overcome such challenges, it is first necessary to understand that a percent is a hundredth part of something whole. This whole can be, for example, the sum of several numbers.
How to determine the percentage of the amount
You will need
  • - the numbers that make up the amount;
  • - any computing device;
  • - a sheet of paper;
  • - a pencil or pen.
Instruction
1
For example, the need to find out what the percentage of the total is each of the summands. Indicate the number that need to be folded in any letters. For example, let it be integers a, b and c, and the sum of them is equal to d. Then the sum d, which in scientific literature is usually denoted as σ, is equal to a+b+c.
2
Find one percent of the amount. This requires a number d divided by 100. Now you need to find what percentage of the total is each of the summands. That is, you need to consistently know how many times the numbers a, b and c "fit" in a numerical value of 1%. To do this, divide by this value each of the components.
3
Such tasks are convenient to solve by using proportions. Take the number of d for 100%, and the desired summand for x will the ratio d=100% and=x. Remember how to write the equation with such terms. The unknown variable is found by multiplying the number and 100% and dividing the resulting works on the amount of d That can be expressed by the equation x=a*100/d.
4
In exactly the same way we can solve the problem, where a known amount and what percentage of it is each of the summands. In this case, as unknown indicate the number and proportion will look like the following: d=100%, x=35%. Write down the equation as a fraction, the numerator of which is the product of the number d and 35%, and the denominator is 100%, i.e. in this case x=d*35/100.
Note
The numerical value of the percentage can be expressed as a decimal. For example, to find 40% is the same as to find how much is it to 0.4. That is the number you need to multiply by 0.4.
Useful advice
Many of these problems can be solved without the help of computing devices. However, in many cases, you may need a calculator. If it has no functions for calculating percentages, the calculations are carried out as described in methods. It is more convenient to use the equation of proportion.
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