Answer: 20 percent of 42 is 8.4

Assume the unknown value is 'Y'

Y = 20 x 42%

Y = 20 x 42 100

Y = 8.4

Answer: 20 percent of 42 is 8.4

Here is an easy method to solve percentage calculations such as what is 20% of 42. You can solve this type of calculation with your own values by entering them into the calculator's fields, and click *'Calculate'* to get the result and explanation.

Percentages are similar to fractions with an important difference. In fractions the whole is represented by the denominator (e.g. the number 5 in the fraction of ^{1}/_{5}). In percentages, the whole is represented by the number 100. In fact, 'per cent' means 'per 100' or 'for each 100'.

To solve the problem above, let's convert it into equation form: **__ = 20% x 42**

In this example, the number 42 represents the whole and so, as a percentage, it would be equal to 100%. Written as a ratio, we would get: 100% : 42

If a student took a 42 question test and they got every answer correct, as a percentage they would get a 100% score on the test.

In our problem we have to evaluate the 20 percent of 42. For now, let's call this unknown value 'Y'. Written as a ratio, we would get: **20% : Y**

To see a relationship between these two ratios, let's combine them into an equation: **100% : 42 = 20% : Y**

It is critical that both of the % values should be on the same side of a ratio. For instance, if you decide to put the % value on the right side of a ratio, then the other % value should also be on the right side of its ratio.

'42 : 100% and Y : 20%' is correct.

'42 : 100% and 20% : Y' is wrong.

Let's solve the equation for Y by first rewriting it as: **100% / 42 = 20% / Y**

Drop the percentage marks to simplify your calculations: **100 / 42 = 20 / Y**

Multiply both sides by Y to transfer it on the left side of the equation: **Y ( 100 / 42 ) = 20**

To isolate Y, multiply both sides by 42 / 100, we will have: **Y = 20 ( 42 / 100 )**

Computing the right side, we get: **Y = 8.4**

This leaves us with our final answer: **20% of 42 is 8.4**