# Percentages

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

Example 1

1% = 0,01

13% = 0,13

57% = 0,57

100% = 1,00

123% = 1,23

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0,14 = 14%

2,34 = 234%

0,005 = 0,5%

23,00 = 2300%

1,09 = 109%

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 2

Calculate 7% of 490.

Convert percent to decimal form 7% = 0.07

0.07 · 490 = 34.3

The percentage equation consists of three parts: Original value, Percent coefficient and Result.

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

Of which number is 25% 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 of 30 is 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%

Most percentages can be calculated this way. All you have to do is identify the number or value we are starting from, that is, where the percentage is from.

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