Number
- Percentage ChangeUse to find the percentage increase or decrease between two values.
- Simple InterestCalculate interest (I) given the Principal (P), Rate (R) and Time (T).
Key concepts: **Prime Numbers**: A number greater than 1 with exactly two factors: 1 and itself (e.g., 2, 3, 5, 7, 11)., **Rational vs Irrational**: Rational numbers can be written as a fraction (e.g., 0.5, 7, 1/3). Irrational numbers cannot (e.g., $\pi$, $\sqrt{2}$)., **Set Notation**: $\cap$ is intersection (elements in both sets), $\cup$ is union (elements in either set), and $\in$ means 'is an element of'.
Exam tips
- When using a calculator for multi-step problems, use the full answer from the previous step to avoid rounding errors.
Algebra and graphs
- Rules of IndicesWhen multiplying powers with the same base, add the indices.
- Nth Term of a Linear SequenceFind any term in a sequence where 'a' is the first term and 'd' is the common difference.
Key concepts: **Simplifying Expressions**: Collect 'like terms' (terms with the same variable and power) by adding or subtracting their coefficients., **Solving Linear Equations**: Isolate the unknown variable by performing the same inverse operation on both sides of the equation., **Factorising**: The reverse of expanding brackets; find the highest common factor (HCF) of all terms and place it outside the bracket.
Exam tips
- When solving simultaneous equations, always substitute your solutions back into the original equations to check your answer.
Coordinate geometry
- Gradient of a LineCalculates the steepness of a line passing through two points.
- Equation of a Straight LineRepresents a straight line where 'm' is the gradient and 'c' is the y-intercept.
Key concepts: **Gradient (m)**: Measures the steepness. Positive gradient slopes up from left to right, negative slopes down., **Y-intercept (c)**: The point where the line crosses the y-axis. The coordinates are (0, c)., **Parallel Lines**: Lines that never intersect and have the exact same gradient (m).
Exam tips
- Be careful with negative signs when calculating the gradient. A common mistake is mixing up the order of coordinates.
Geometry
- Sum of Interior AnglesFind the sum of all interior angles in any polygon with 'n' sides.
Key concepts: **Angle Properties**: Angles on a straight line sum to 180°. Angles around a point sum to 360°. Vertically opposite angles are equal., **Parallel Line Angles**: Corresponding angles are equal ('F' shape), alternate angles are equal ('Z' shape), and co-interior angles sum to 180° ('C' shape)., **Bearings**: Measured clockwise from North and always written as a 3-figure number (e.g., 045°).
Exam tips
- If a question asks you to 'give a reason' for your angle calculation, you must state the geometric rule you used.
Mensuration
- Area of a TrapeziumFind the area of a trapezium where 'a' and 'b' are the parallel sides and 'h' is the height.
- Circumference of a CircleorCalculate the distance around the outside of a circle using radius 'r' or diameter 'd'.
- Volume of a CylinderCalculates the space inside a cylinder using the radius 'r' and height 'h'.
Key concepts: **Perimeter**: The total distance around the outside of a 2D shape., **Area**: The amount of space inside a 2D shape, measured in square units (e.g., cm²)., **Volume**: The amount of space a 3D object occupies, measured in cubic units (e.g., m³).
Exam tips
- Always check if a question gives the radius or the diameter of a circle. Using the wrong one is a very common mistake.
Trigonometry
- Pythagoras' TheoremFind a missing side in a right-angled triangle when two sides are known. 'c' is always the hypotenuse.
- SOH CAH TOAUse to find a missing side or angle in a right-angled triangle.
Key concepts: **Right-Angled Triangle**: A triangle with one 90° angle. The longest side, opposite the right angle, is the hypotenuse., **Labelling Sides**: Identify the Hypotenuse (opposite right angle), Opposite (opposite the angle of interest), and Adjacent (next to the angle of interest).
Exam tips
- Before starting any trigonometry questions, make sure your calculator is in Degrees (DEG) mode.
Transformations and vectors
- Translation VectorDescribes a translation. The top number is horizontal movement (right is +) and the bottom is vertical (up is +).
Key concepts: **Reflection**: A mirror image of a shape across a given mirror line (e.g., y-axis, x=2)., **Rotation**: A turn described by a centre of rotation, an angle (e.g., 90°), and a direction (clockwise or anticlockwise)., **Enlargement**: Changes the size of a shape. Described by a centre of enlargement and a scale factor.
Exam tips
- For rotations, it can be helpful to use tracing paper to perform the rotation and then mark the new position on the grid.
Probability
- Probability of an EventCalculates the likelihood of a single event occurring.
- Complementary EventsThe probability of an event not happening is 1 minus the probability that it does happen.
- Expected FrequencyEstimates how many times an event is expected to occur over a number of trials.
Key concepts: **Probability Scale**: Probability is always a value between 0 (impossible) and 1 (certain)., **Relative Frequency**: An estimate of probability based on experimental results: $\frac{\text{number of times event occurs}}{\text{total number of trials}}$.
Exam tips
- Probability answers can be fractions, decimals, or percentages. Always simplify fractions unless the question says otherwise.
Statistics
- MeanCalculates the mean average of a set of discrete data.
Key concepts: **Averages**: Mean (sum ÷ count), Median (middle value of ordered data), and Mode (most frequent value)., **Range**: A measure of spread, calculated as the highest value minus the lowest value., **Correlation**: Describes the relationship between two variables on a scatter diagram (positive, negative, or no correlation).
Exam tips
- To find the median, you MUST arrange the data in order of size first. Forgetting this step is a very common error.