Calculating the percentage of a number is one of the fundamental topics that everyone goes through at school in mathematics lessons. But this does not mean that everyone masters it with ease. In fact, the topic is simple, the main thing is to know the proven methods for calculating the whole by part and percent of the whole.
1% is a hundredth part of the whole, so knowing this value, you can easily calculate the value of the part. For example, 15% of the number 60 can be calculated as follows: take 60 as 100 percent. Then 1% is 60/100 - 0.6. 15% is thus - 0.615=9. This is the first way to calculate a percentage of a number.
The second way is to make a proportion. 15 is to 100 as x is to 60, i.e. 15/100=x/60. There are two ways to solve the composed proportion:
- Transform it into the expression x=1560/100. And again it turns out: x=9.
- Make another transformation, in 2 steps: 100x=1560, that is, the numbers in proportions are multiplied crosswise. From this expression we get the following: 100x=900. Therefore, x=9.
If you need to find out what percentage of a number is another number,the formula is also very simple. Let's take the numbers 70 and 13 as an example. Let 70 be 100% and 13 be x. Then 13/70=x/100. You can solve this proportion in familiar ways.
70x=13100; 70x=1300; If rounded to the second decimal place, it turns out that x=18.57%.
If you know the percentage of a certain number and you need to find this number, then this problem can be solved.
For example, 16% is 32. What is an integer? Again, we make up the proportion: 16% is related to 100%, just like 32 to x. 16/100=32/x; 16x=3200; x=3200/16=200.
If the condition of the problem is such that the number A is a certain percentage of the number B, which must be calculated, then another very simple formula is applied. A / B100% - this will be the answer. For example, you need to find out what percentage of the number 87 is from the number 329.
Calculating the result using the formula, we get 87/329100%=26.44%. If the formula is forgotten at the right time, proportions will come to the rescue again: 87 is related to 329, as x is related to 100%, that is, 87/329=x/100. Transforming this proportion, we get 329x=87100; 329x=8700; x=8700/329=26, 44%.
Well, the simplest proportions are always on everyone's lips and in their heads: one fifth is 20%, one tenth is 10%, half and a quarter are 50% and 25% respectively. For some, it is more convenient and clearer to think in parts, while for others it is easier to operate with percentages. There is no big difference between one half and 50%.
With a calculator it will be easy andsimple, because there is even a special button that allows you to calculate percentages.
Of course, all these tasks are just to reinforce the theory. But you may need to calculate the percentage of a number in life. At sales to find out if the 30% discount is worth grabbing onto the item, or is it a meager amount. You can find out what the price was before the discount, as well as double-check the sellers - after all, they often take advantage of the inattention of buyers and indicate extremely attractive numbers on the price tags.
Calculate a percentage of a number may also be needed when calculating taxes, of course, for those who keep track of such things. And, of course, accountants, economists, stockbrokers and analysts constantly face the calculation of interest. In fact, even housewives deal with interest all the time without realizing it.
In a word, the topic is simple, although it seems very difficult at first glance. However, when understanding comes, the tasks concerning the calculation of percentages of a number and a whole by a part will seem like seeds. You just need to fill your hand and move your brain a little.
