Maths (school) · Part 01
Number and ratio
Fractions, percentages, ratio, powers and standard form.
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- BIDMASThe order you work through a calculation: Brackets, Indices (powers), Division and Multiplication, then Addition and Subtraction.
- Adding fractionsTo add fractions, first make the bottom numbers (denominators) the same, then add the top numbers (numerators).
- Percentage of an amountA percentage means 'out of 100'. To find a percentage of an amount, break it into easy chunks like 10% and 1%.
- Percentage changeA way to show how much something went up or down compared with where it started.
- RatioA way to compare amounts. 2:3 means for every 2 parts of one thing there are 3 parts of another.
- Direct proportionTwo amounts are in direct proportion when doubling one also doubles the other.
- Laws of indicesRules for combining powers. Add the powers when multiplying, subtract when dividing, and multiply them for a power of a power.
- Standard formA short way to write very big or very small numbers as a number between 1 and 10 times a power of 10.
- HCF and LCMThe highest common factor (HCF) is the biggest number that divides into both numbers. The lowest common multiple (LCM) is the smallest number both go into.