Percentages Math

Introduction to percentages in math:

In mathematics, a percentage(%) is a way of expressing a number as a fraction of 100 (per cent meaning "per hundred"). Percentages are used to express how large/small one quantity is, relative to another quantity. The first quantity usually represents a part of, or a change in, the second quantity, which should be greater than zero. (Source: From Wikipedia).

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Different forms of solving percentages in math:


Fraction or Decimal to percent conversion means, we have to multiply by 100.

Percentage increase = (increase/ original amount)*100 %

Percentage decrease = (decrease / original amount) * 100 %

Let us take an example; an increase of `$`  5 on a price of `$` 80 is an increase by a fraction of 5 / 80 = 0.0625. Expressed as a percentage, this is therefore a 6.25% increase.

Now, we are going to see some of the problems on percentages in math.

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Math percentages problems:


Example problem 1:

Express the decimal number 0.06 in percentage:

Solution:

Multiply 100 with the given decimal number.

0.06 = 0.06*100 %

= 6%

So, the answer is 6%.

Example problem 2:

Express the fraction number (3/4) in percentage:

Solution:

Multiply 100 with the given fraction number.

3/4 = (3/4) *100 %

= 75%

So, the answer is 75%

Example problem 3:

What is 20% of 80?

Solution:

The original number is 80. 20% means 20/100. So, 20/100 is multiplied with the original number.

20% of 80 = (20/100)*80

= 16.

So, 20% of 80 is 16.

Example problem 4:

Mani bought a stock for `$` 60, and she sold it for` $` 72. He made a profit of what percent?

Solution:

Profit = stock sold price – stock original price

Profit = `$` 72 - `$` 60

Profit = `$` 12

Profit percentage = (profit / original price) *100

Profit percentage = (12 / 60)*100

Profit percentage = 20%

Example problem 5:

10% of a certain number is 100.  Find the number.

Solution:

Let us take a number be ‘x’.

10% of a number means (10/100) is multiplied with x.

So, it can be written as

(10/100)*x = 100

(1/10)*x = 100

x = 1000

So, the number is 1000.