Maths

Mean

Add all the numbers together, then divide by how many numbers there are.

Median

Put the numbers in order and find the middle number.

Mode

The number that appears most often.

Range

Biggest number minus smallest number.

Angles

Angles on a straight line 180°

Angles around a point 360°

Angles in a triangle 180°

Angles in a quadrilateral 360°

Area of a rectangle

Length × width

Area of a triangle

You multiply the base by the height, then divide your answer by 2 to find the area of a triangle.

Speed

Distance ÷ time

Percentage to decimal:

divide by 100.

To find 10% of a number,

divide by 10.

To find 50% of a number,

divide by 2.

To find 25% of a number,

divide by 4.

Positives and negatives

• Positive × positive = positive.

• Negative × negative = positive.

• Positive × negative = negative.

• Negative × positive = negative.

What is an acute angle?

An angle less than 90°.

Example: 45°

What is a right angle?

An angle of exactly 90°.

What is an obtuse angle?

An angle greater than 90° but less than 180°.

Example: 120°

What is a straight angle?

An angle of exactly 180°.

What is a reflex angle?

An angle greater than 180° but less than 360°.

Example: 270°

What are vertically opposite angles?

Angles opposite each other when two lines cross; they are equal.

Angles in a quadrilateral add up to?

360°

What are co-interior angles?

Angles inside parallel lines on the same side of a transversal; they add up to 180°.

What is an even number?

A whole number that is divisible by 2 with no remainder.

Examples: 2, 4, 6, 8, 10, 12.

Exam tip: Even numbers always end in 0, 2, 4, 6 or 8.

What is an odd number?

A whole number that is not divisible by 2 exactly.

Examples: 1, 3, 5, 7, 9, 11.

Exam tip: Odd numbers always end in 1, 3, 5, 7 or 9.

What is a prime number?

A whole number greater than 1 that has exactly two factors: 1 and itself.

Examples: 2, 3, 5, 7, 11, 13, 17, 19.

Exam tip: 2 is the only even prime number.