Algebra and Sequences

Algebra and sequences appear regularly on the SET 11+ maths papers. The SET is known for testing problem-solving and reasoning skills, and algebra questions are a key part of that. You may be asked to find unknown values, write expressions, and spot patterns in number sequences. On Stage 2, you will need to show your working when solving equations. This lesson covers all the algebra and sequence skills you need.

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What Is Algebra?

Algebra uses letters to stand for unknown numbers. Instead of writing "a number", we write a letter such as n, x, or a.

Expression	Meaning
3n	3 × n (three times n)
n + 7	n plus 7
2n - 4	Two times n, minus 4
n/5	n divided by 5
n²	n × n (n squared)

Remember: In algebra, we do not usually write the multiplication sign. We write 3n instead of 3 × n.

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Simplifying Expressions

To simplify, collect like terms — group the letters that are the same.