Algebra

Algebra is the branch of maths where we use letters to stand for unknown numbers. It lets you write general rules and solve problems where you don't know all the values yet. This topic is introduced in Year 6.

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Variables and Expressions

A variable is a letter that stands for a number we don't know yet (or that can change).

An expression is a combination of numbers, variables, and operations.

• 3n means 3 x n (3 multiplied by the variable n).
• 2a + 5 means double a, then add 5.
• p - 7 means p take away 7.

Evaluating an expression: replace the variable with a given value and calculate.

• If n = 4, find 3n + 2: 3 x 4 + 2 = 12 + 2 = 14.
• If a = 6, find 2a - 3: 2 x 6 - 3 = 12 - 3 = 9.

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Formulae

A formula shows the relationship between variables. You substitute (plug in) known values to find unknown ones.