Adding and multiplying percents

Adding and multiplying percents

Knowing how to add and multiply percentages is very useful in our daily life. Do you know how much sales tax you are going to pay for your new purchases? What is the sale price after discount? How do banks calculate interest? We will learn more in this section.
Basic concepts: Percents, fractions, and decimals,
Related concepts: Comparing and ordering rational numbers, Solving problems with rational numbers in decimal form, Solving problems with rational numbers in fraction form,

Lessons

  • 1.
    One video game is $25 before 12% sales tax. How much is 4 video games after tax?
  • 2.
    WhenKimwasingrade5,shewas130cmtall.Ingrade6,shewas20Ingrade7,herheighthasincreasedby15When Kim was in grade 5, she was 130 cm tall. In grade 6, she was 20% taller than last year. In grade 7, her height has increased by 15%.
    a)
    How tall was Kim when she was in grade 7?

    b)
    Did Kim’s height increase by 35% from grade 5 to grade 7? Explain.

  • 3.
    A bank pays a compound interest of 5% to any account with $10000 annually. How much will be there in an account with $10000 after 3 years?
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13.
Percents
13.1
Representing percents
13.2
Percents, fractions, and decimals
13.3
Percent of a number
13.4
Adding and multiplying percents
13.5
Taxes, discounts, tips and more
13.6
Simple interest
UK Year 9 Maths
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