Revision notes · Maths
Fractions are one of the most important building blocks in GCSE Maths, and they come up everywhere — from algebra to probability.
To simplify a fraction, you need to find the highest common factor (HCF) of the numerator and denominator, then divide both by it. For example, to simplify 1824, the HCF of 18 and 24 is 6, so 1824 becomes 34.
When adding or subtracting fractions, you must have the same denominator. Find the lowest common multiple (LCM) of both denominators, rewrite each fraction with that denominator, then add or subtract the numerators.
For multiplying, it's straightforward — multiply the tops together and the bottoms together. For dividing, remember KFC: Keep the first fraction, Flip the second, and Change the ÷ to ×.
Mixed numbers (like 2¾) should be converted to improper fractions before doing any calculation. Multiply the whole number by the denominator and add the numerator: 2¾ = (2 × 4 + 3)/4 = 114.