12 is 40 percent of what number? This calculator provides an easy method to solve percentage calculations.

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.

This is a simple method for solving percentage equations. Use this calculator for business, classroom assignments, when shopping, and in general daily life where percentage calculations are needed.

Assume the unknown value is 'Y'

100% / Y = 40% / 12

100 / Y = 40 / 12

100 = ( 40 / 12 ) Y

100 = 40 Y

30 = Y

Answer: 12 is 40 percent of 30

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: **12 = 40% x __**

In this example, the number that represents the whole is unknown, which we will call 'Y'. As a percentage, it would be equal to 100%. Written as a ratio, we would get: **100% : Y**

If a student took a test with a number of questions equal to Y, and they got every answer correct, as a percentage they would get a 100% score on the test.

It is already given in this problem that 12 is equivalent to 40%. Written as a ratio, we would get: **40% : 12**

To see a relationship between these two ratios, let's combine them into an equation: **100% : Y = 40% : 12**

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.

'Y : 100% and 12 : 40%' is correct.

'Y : 100% and 40% : 12' is wrong.

Let's solve the equation for Y by first rewriting it as: **100% / Y = 40% / 12**

Drop the percentage marks to simplify your calculations: **100 / Y = 40 / 12**

Multiply both sides by Y to move Y on the right side of the equation: **100 = ( 40 / 12 ) Y**

Simplifying the right side, we get: **100 = 40 Y**

Dividing both sides of the equation by 40, we will arrive at: **30 = Y**

This leaves us with our final answer: **12 is 40 percent of 30**