# How to calculate percentage?

Learn how to work out percentages easily with this step-by-step instructions.

Remember:^{1.} When you say x%, it means a number with x as the numerator and 100 as the denominator i.e., x% = ^{x}/_{100}

and^{2.} x% of y = ^{x}/_{100} × y

#### Example: Let's find 15% of 90

15% of 90 = ^{15}/_{100} × 90 = 0.15 × 90 = 13.5

#### Next: How to find the percentage of one number with respect to another?

e.g., What is the percentage of boys with respect to the total class strength of 60 if there are 20 boys in the class?

- First we write the no. of boys to total students as a ratio i.e.,
^{20}/_{60}
- Multiply both numerator and denominator by 100. We do this so as to get a number with denominator 100

^{20 × 100}/ _{60 × 100}
- Rewriting the expression, we have
^{20 × 100}/ _{60} × ^{1}/ _{100}
- or,
^{2000}/ _{60} × ^{1}/ _{100}
- or, 33.33 ×
^{1}/ _{100}
- or,
^{33.33}/ _{100} = 33.33% (Refer note 1. above)

#### Finally: Let's learn how to solve percentage problems of the form "15% of what number is 300?"

Let the number be **x**

- We have 15% of x = 300
- or,
^{15}/_{100} × x = 300 (Refer note 1. and 2. above)
- or, x =
^{300 × 100}/ _{15} (by multiplying both sides by 100 and dividing both sides by 15)
- or, x =
^{30000}/ _{15} = 2000