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Percent and Operations

In this topic we will cover the basic operations of a percent - percent of a number, number when percent is known. Practical applications such as tip calculation, discounts, and rates are also covered.

Topic: What is 'a%' of 'b'

  • To find the percent of a number, write the percent as a fraction with 100 as the denominator and then multiply the fraction with the number

  • E.g. To find 5% of 20,
    Write 5% as a fraction with 100 as denominator.
    5% = 5
           100 

    Then, multiply 5/100 with 20

    Or, 5 x 20
        100

Topic: 'a%' of what number is 'b'

  • To solve questions such as 5 is 25% of what number:

     

    Let the number be n

    So, 5 is 25% of n

    Or, 25 x n = 5
         100

    Find n.

Topic: What percent of 'a' is 'b'?

  • To find what percent of ‘a’ is ‘b’, let the percent be n%

    E.g. n% of 20 is 5.
    Or, n x 20 = 5
        100
    Evaluate n.

Topic: Percent Applications

  • To make calculations easier round off the decimal costs to the nearest whole number

  • If the digit to the right of the digit to be rounded is 5 or greater, we will add 1 to the digit to be rounded. If digit is 4 or less, the digit to be rounded remains the same

  • Cost of a product after discount = Regular price of the product - Discount on the product

  • Cost of a product after sales tax = Regular price of the product + Sales tax on the product
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