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Numbers Big and Small
Numbers Big and Small
Imagine measuring ingredients for a recipe: you need 2.5 cups of flour, not just 2 or 3. Decimals give us precision between whole numbers. From counting change (£3.47) to measuring distances (5.2km), decimals are everywhere in daily life.
What is a decimal?: A number with a decimal point showing parts of a whole. The digits after the point represent tenths, hundredths, thousandths, etc.
Mathematics glossary
- What is a decimal?
- A number with a decimal point showing parts of a whole. The digits after the point represent tenths, hundredths, thousandths, etc.
What Are Integers and Decimals?
The number 123.456 = 100 + 20 + 3 + 0.4 + 0.05 + 0.006
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Common Mistakes to Avoid
❌ Wrong: 3.4 + 2.56 = 5.10
✅ Right: 3.4 + 2.56 = 5.96
Always align decimal points when adding
❌ Wrong: 0.5 × 0.2 = 1.0
✅ Right: 0.5 × 0.2 = 0.1
Decimal × decimal usually gives smaller answer
❌ Wrong: 4 ÷ 0.5 = 2
✅ Right: 4 ÷ 0.5 = 8
Dividing by decimal less than 1 gives larger answer
Now try it yourself
Quiz · Question 1 of 14
What is the value of the digit 4 in the number 12.345?
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This topic in real past papers
Every real exam question we've found on integers & decimals, with a full worked answer.
AQA Paper 1
Every sitting we have full papers for opens with at least one quick non-calculator arithmetic question involving fractions, decimals, or both.
Edexcel Paper 1
Two of the three sittings we have full papers for open with a pure non-calculator arithmetic question, and June 2023 tests it twice in the first two questions of the paper.