Percentages

The percentage of something is one hundredth of it. That is, 1% = 1/100 = 0,01. The decimal form of a percentage will be used to calculate percentages.

It is easy to calculate percentages in decimal form. For example, 20% of 50 is 0,2 · 50 = 10. So we multiply the number by a decimal form of percentage.

Example 3

Let's calculate how much is 20% of 120.

Original value = 120

Percent coefficient = 0,2

Result = x

The equation is obtained by multiplying the original number by a percentage coefficient equal to the result:

0.2 · 120 = x

24 = x

Calculate 25% of 40?

Original number = x

Percent coefficient = 0,25

Result = 40

Now, we do not know the figure from which 25% has been taken from. So we mark it as unknown by the letter x. However, the equation is formed in exactly the same way.

0,25 · x = 40 || : 0.25

x = 40 / 0,25

x = 160

What percentage is 30 of 270?

Original number = 270 (That is, what we compare to)

Percent coefficient = x

Result = 30 (What we compare)

x · 270 = 30 || : 270

x = 30/270

x ≈ 0.1111 ≈ 0.11 = 11%