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Key Stage 3 Number
Decimal Arithmetic
Calculate with decimals and choose sensible mental or written strategies.
Key idea
Choose a representation first, then calculate carefully and check whether the answer is reasonable.
What you will learn
Use adding decimals confidently.
Use multiplying decimals confidently.
Use dividing decimals confidently.
Use checking answers confidently.
Success checklist
✓I can explain what decimal arithmetic means.
✓I can choose a suitable method without being told.
✓I can show clear working and check my answer.
Worked example
Simplify 1824.
Step 1
Find a common factor of 18 and 24.
Step 2
Both numbers divide by 6.
Step 3
1824 = 34.
Answer
34
Quick practice
Question 1
Simplify 1525.
Question 2
Round 3.746 to 2 decimal places.
Question 3
Write 4,800 in standard form.
Related resources
These are linked to the wider Number topic for now.