GCSE›AQA GCSE Maths›Mind mapsFractions, Decimals and PercentagesAQA GCSE Maths: Mind mapStudy pack PDFAlso for this subtopic:Revision notesFlashcardsSubtopic testCover factsTerminating decimalsWrite over a power of 10, then simplify0.24=24100=6250.24 = \frac{24}{100} = \frac{6}{25}0.24=10024=256Terminates only if denominator has only 2s and 5s38=0.375\frac{3}{8} = 0.37583=0.375Recurring decimalsSet xxx equal to the decimalMultiply by 10n10^n10n for nnn repeating digitsSubtract the original equation0.7˙=790.\dot{7} = \frac{7}{9}0.7˙=970.3˙5˙=35990.\dot{3}\dot{5} = \frac{35}{99}0.3˙5˙=9935Percentage ofPercentage means out of 100Percentage to decimal: ÷100Percentage acts as an operator: multiply15% of 80 =0.15×80=12= 0.15 \times 80 = 12=0.15×80=12Percentagesfractions and decimals%÷100×1.2Percentage changeChange ÷ original × 100Increase by xxx%: multiply by 1+x1001 + \frac{x}{100}1+100xDecrease by xxx%: multiply by 1−x1001 - \frac{x}{100}1−100xSuccessive changes: multiply the multipliersReverse: original = final ÷ multiplierInterestSimple: same amount each year, linearI=PRT100I = \frac{PRT}{100}I=100PRTCompound: A=P(1+r100)nA = P\left(1 + \frac{r}{100}\right)^nA=P(1+100r)nCompound grows exponentiallyCompounded quarterly: rate ÷ 4, time × 4Exam tipsAlways simplify fractions fullySubtract the original equation for recurring decimalsDivide by the original, not the new valueUse multipliers to cut arithmetic errors