Bitesize has changed! We're updating subjects as fast as we can. Visit our new site to find Bitesize guides and clips - and tell us what you think!

Home > Maths > Algebra > Introduction to formulas


Introduction to formulas


Terms and expressions

Algebraic terms and expressions

In algebra, letters are used when numbers are not known.

Algebraic terms, like 2s or 8y, leave the multiplication signs out. So rather than '2 × s', write 2s, rather than '8 × y' write 8y.

A string of numbers and letters joined together by mathematical operations such as + and - is called an algebraic expression.

  • r + 2s means an unknown number 'r', plus 2 lots of an unknown number 's'.


Q1. Say that 'g' is the cost of child admission, and 'k' is the cost of adult admission to the zoo.

a) How much does it cost for the Khan family of 3 children and 3 adults to visit the zoo?

b) Write an algebraic expression for the cost for the Norman family of 5 children and 4 adults to visit the zoo.


a) Cost for 3 children = 3g
Cost for 3 adults = 3k
Total cost = 3g + 3k

b) 5g + 4k


Introduction to formulas activity

Time to formulate a new revision plan!


Gut Instinct

Can you match Viral Vinnie's appetite for English, Maths and Science?

BBC © 2014 The BBC is not responsible for the content of external sites. Read more.

This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.