- Maths Help
- AlgebraToggle Dropdown
- DecimalsToggle Dropdown
- Place value
- Comparing and ordering decimals
- Rounding to a place
- Significant figures
- Standard form and engineering notation
- Adding decimals
- Subtracting decimals
- Multiplying decimals
- Dividing decimals
- Converting decimals to fractions
- Converting decimals to percents
- Converting between decimals, fractions and percents
- Ordering decimals, fractions and percents

- FractionsToggle Dropdown
- Understanding fractions
- Simplifying (reducing) fractions
- Equivalent fractions
- Comparing fractions
- Ordering fractions
- Mixed numbers and improper fractions
- Adding fractions
- Subtracting fractions
- Adding and subtracting mixed numbers
- Multiplying fractions
- Dividing fractions
- Multiplying and dividing mixed numbers
- Converting fractions to decimals
- Converting fractions to percents
- Converting between fractions, decimals and percents
- Ordering fractions, decimals and percents

- IntegersToggle Dropdown
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- Area of squares, rectangles and triangles
- Area of circles
- Surface area of cubes, cuboids and triangular prisms
- Surface area of cylinders
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- Percents
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In this module, you can study how to calculate percent increase and percent decrease.

The video above shows a quick method for calculating percent increase or decrease. At the end, she quickly converts the decimal number answer to a percent by moving the decimal point two places to the right. If you're unclear how to do this, see "Converting decimals to percents" under the "Decimals" tab.

100 reduced by 25% is 75, but 75 increased by 25% is not 100!

If an house price increases 20% one year and 10% the next year, it has gone up 32% (not 30%!) of the original value.

- Study percent changeStudy percent change at mathgoodies.com, then try a few problems on your own. This page expects you to understand the concept of "absolute value", which is talked about in the link below.
- Study percent change in more depthRead more about percent increase and decrease (or percent change) at mathsisfun.com. At the end you can try some problems.
- Quiz yourself on percent increase and decreaseTry these percent increase and decrease problems at onlinemathlearning.com.