You can solve this type of calculation with your own values by entering them into the calculator's fields, clicking 'calculate' and getting your answer!
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: 18 = __% x 20
In this example, the number 20 represents the whole and so, as a percentage, it would be equal to 100%. Written as a ratio, we would get: 100% : 20
If a student took a 20 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 discover what percentage 18 is out of a whole of 20. For now, let’s call this unknown percentage value "Y". Written as a ratio, we would get: Y% : 18
To see a relationship between these two ratios, let’s combine them into an equation: 100% : 20 = Y% : 18
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.
"20 : 100% and 18 : Y%" is correct.
"20 : 100% and Y% : 18" is wrong.
Let’s solve the equation for Y by first rewriting it as: 100% / 20 = Y% / 18
Drop the percentage marks to simplify your calculations: 100 / 20 = Y / 18
Multiply both sides by 18 to isolate Y on the right side of the equation: 18 ( 100 / 20 ) = Y
Computing the left side, we get: 90 = Y
This leaves us with our final answer: 18 is 90% of 20