 # How to calculate percentage ? Calculate percentage referred to as percent, is a fraction of a number out of 100%. The term “percentage” was adapted from the Latin word “per centum”, which means “by the hundred”. In other words, it is the relation between part and whole where the value of whole is always taken as 100. For example, 45% represents 45 out of 100, or 45% of the total amount.

Things to know

## How to calculate a percentage ?

The following formula is a common strategy to calculate a percentage:

1. Determine the total amount of what you want to find a percentage:

If you want to calculate the percentage of days it rained in a month, you would use the number of days in that month as the total amount. So, let’s say we are evaluating the amount of rain during the month of April’s 30 days.

1. Divide the number to determine the percentage:

Let’s say that it rained 15 of the 30 days in April. You would divide 15 by 30, which equals 0.5.

1. Multiply the value by 100:

Continuing with the above example, you would multiply 0.5 by 100. This equals 50, which would give you the answer of 50%. So, in April, it rained 50% of the time.

Percentage= (Value/Total Value)×100

For a price or percentage increase:
[(New Price – Old Price)/Old Price] x 100

For a price or percentage decrease:
[(Old Price – New Price)/Old Price] x 100

## How to calculate percentage difference ?

You can use percentages to compare two different items that are related to each other. This calculation would give you the percent difference between the two product prices.

The following is the formula used to calculate a percentage difference:

|V1 – V2|/ [(V1 + V2)/2] × 100

In this formula, V1 is equal to the cost of one product, and V2 is equal to the cost of the other product.

## Example: What is 10% of 150?

Convert the problem to an equation using the percentage formula: P% * X = Y
P is 10%, X is 150, so the equation is 10% * 150 = Y
Convert 10% to a decimal by removing the percent sign and dividing by 100: 10/100 = 0.10
Substitute 0.10 for 10% in the equation: 10% * 150 = Y becomes 0.10 * 150 = Y
Do the math: 0.10 * 150 = 15
Y = 15
So 10% of 150 is 15
Double check your answer with the original question: What is 10% of 150? Multiply 0.10 * 150 = 15