REVISION NOTES

IGCSE Edexcel Mathematics A

1.6 Percentages

1.6.1 Understand that ‘percentage’ means ‘number of parts per 100’

edexcel_igcse_mathematics a_topic 06_percentages_001_introduction to percentage

1.6.2 Express a given number as a percentage of another number

1.6.3 Express a percentage as a fraction and as a decimal

To convert a percentage into a fraction, simply write the given percentage over a denominator of 100, then cancel down if appropriate.

  • 50%= ½ or 0.5
  • 25% = ¼ or 0.25
  • 20% = ⅕ or 0.2
  • 100% = or 1 (both fraction and decimal makes 1)
edexcel_igcse_mathematics a_topic 06_percentages_002_conversion between fraction and percentage

1.6.4 Understand the multiplicative nature of percentages as operators

1.6.5 Solve simple percentage problems, including percentage increase and decrease

edexcel_igcse_mathematics a_topic 06_percentages_003_percentage change

Percentage increase or decrease may be calculated very efficiently using a multiplying factor. This may either be greater than 1 (increase) or less than 1 (decrease).

 

Example 1:

3% increase = 1 + 0.03 = 1.03

 

Example 2:

3% decrease = 1 – 0.03 = 0.97

1.6.6 Use reverse percentages

To reverse the calculation, simply divide by the multiplying factors.

1.6.7 Use compound interest and depreciation

edexcel_igcse_mathematics a_topic 06_percentages_004_compound interest

1.6.8 Use repeated percentage change (Higher Tier Only)

1.6.9 Solve compound interest problems (Higher Tier Only)

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1.1 Integers

1.2 Fractions

1.3 Decimals

1.4 Powers and Roots

1.5 Set Language and Notation

1.6 Percentages

1.7 Ratio and Proportion

1.8 Degree of Accuracy

1.9 Standard Form

1.10 Applying Numbers

1.11 Electronic Calculator

2.1 Use of Symbols

2.2 Algebraic Manipulation

2.3 Expressions and Formulae

2.4 Linear Equations

2.5 Proportion (Higher Tier Only)

2.6 Simultaneous Linear Equations

2.7 Quadratic Equations

2.8 Inequalities

3.1 Sequences

3.2 Function Notation (Higher Tier Only)

3.3 Graphs

3.4 Calculus (Higher Tier Only)

4.1 Angles, Lines & Triangles

4.2 Polygons

4.3 Symmetry

4.4 Measures

4.5 Construction

4.6 Circle Properties

4.7 Geometric Reasoning

4.8 Trigonometry and Pythagoras’ Theorem

4.9 Mensuration of 2D Shapes

4.10 3D Shapes and Volumes

4.11 Similarity

5.1 Vectors (Higher Tier Only)

5.2 Transformation Geometry

6.1 Graphical Representation of Data

6.2 Statistical Measures

6.3 Probability

7.1 Appendix 1: Foundation Tier Formula Sheet (Given)

7.2 Appendix 2: Foundation Tier Formula Sheet (To Memorise)

7.3 Appendix 3: Higher Tier Formula Sheet (Given)

7.4 Appendix 4: Higher Tier Formula Sheet (To Memorise)

7.5 Appendix 5: Notation

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