Number
The foundation of all mathematics: understanding the different families of numbers, how we represent them, and how they behave.
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The City of Numbers
Welcome to the City of Numbers. You are going to explore every district: the counting numbers you learned as a child, the strange negative mirrors of those numbers, the crowded fractions between them, and the powerful roots that grow deep beneath the surface.
Understanding this map is not just about passing an exam — it is about knowing exactly where you are in any mathematical situation. Have you ever wondered why you cannot divide by zero, or what makes prime numbers special? You are about to find out.
Formula
Think of numbers as the alphabet of mathematics — once you know them, you can read anything
What You Will Learn
You will start by naming the districts of the city — the families every number belongs to — then learn the arithmetic the exam keeps coming back to.
Steps
- 1
Families of number: natural, integer, rational, irrational and real.
- 2
Hidden structure: factors, multiples, primes, prime factorisation, HCF and LCM.
- 3
Accuracy: rounding, decimal places, significant figures, estimation and bounds.
- 4
Fractions, decimals and percentages, including the reverse percentage.
- 5
Ratio and proportion, direct and inverse, and compound measures.
- 6
Indices, standard form and surds, then money, time and sets.
Formula
The workhorse:
Read it forwards for an increase; divide by the bracket to work backwards.
Practise number now
Interactive visual aids, then real past-paper questions marked on your working like the exam. Free to start.
Practise free on LemmaraLemmara is an independent study tool, not affiliated with or endorsed by Cambridge International Education or Pearson Edexcel. The lessons and worked examples are Lemmara’s own.