With the need to calculate the percentage of peopleIt faces constantly, sometimes even himself without realizing it. And not only in the exam in mathematics, but also, for example, trying to determine what portion of the total family income up utility bills or pay for daycare.
And many need to calculate interest baffled.
Understand that the numbers from which youcalculate percentages - it is always hundred percent. Regardless of whether it is given in the problem, or do you find him, clasped the income of all family members. It may be denoted, for example, a letter or any other letter, and generally can not be denoted.
Find that number 1 percent. To do this, divide the original number by 100. If we take the general formula, the 1 percent of the number and will be equal to a / 100.
Suppose you need to find is not 1 percent, and 20. Then the number of which is designated 1 percent of the set, must be multiplied by the required amount of interest. That is, get well / 100 * 20. For example, your salary is 11 000 rubles. 1% of this number is 110 rubles, and 20% to 2 200 rubles.
For example, in the task requires know howper cent of the original number and the number of b. The percentages that you want to find, as the label's. Find 1%, which would be a / 100. To determine what percentage of the number and the number is b, it is necessary to divide the value obtained. Remember the rules of the division of an integer by a fraction. Necessary number to divide by the numerator of the fraction (in this case a) and the denominator is multiplied by its (in this case 100): x = b / a * 100. For example, the warehouse brought 250 bags of potatoes. 35 storekeeper immediately sent to the store, and he should know how much it is per cent of the total number of bags. Find 1%, which in this problem will be 250/100 = 2.5 bag. Dividing 35 by 2.5, you get the desired value - 14%.