Estimating with Multiplication Made Easy
Year 5 Mathematics Learning to estimate products efficiently Building number sense and confidence
WALT - We Are Learning To
Estimate products using rounding strategies Use front-end estimation with multiplication Check if our answers are reasonable Apply estimation in real-world problems
Success Criteria - How We'll Know We've Succeeded
I can round numbers to the nearest 10 and 100 I can estimate products before calculating I can explain my estimation strategy I can use estimation to check my answers
Mathematical Mindset
"Estimation is like being a maths detective - we look for clues to find answers that make sense!"
What is Estimation?
Making a reasonable guess about an answer Using rounded numbers to calculate quickly Checking if our exact answer makes sense A useful life skill for shopping and planning
Rounding Review - Our Estimation Tool
Round to nearest 10: look at the ones digit 5 or more? Round up! 4 or less? Round down! Examples: 23 → 20, 67 → 70, 45 → 50
Quick Rounding Challenge
Round these numbers to the nearest 10: 34 → ? 78 → ? 65 → ? Show your answers with hand signals!
I Do - Teacher Modelling
Problem: 23 × 47 Step 1: Round both numbers (20 × 50) Step 2: Multiply the rounded numbers (1,000) Step 3: Compare with exact answer (1,081)
More Teacher Examples
Problem: 34 × 28 Round: 30 × 30 = 900 Exact: 952 ✓ Close enough! Problem: 67 × 19 Round: 70 × 20 = 1,400 Exact: 1,273 ✓ Good estimate!
We Do - Guided Practice
Let's estimate together! Problem: 42 × 36 Turn to your partner and discuss: What should we round each number to? What's our estimated answer?
We Do - Let's Check Our Thinking
42 rounds to 40 36 rounds to 40 40 × 40 = 1,600 Exact answer: 1,512 Our estimate was very close!
Think and Share
When might estimation be more useful than exact calculation? Think of a real-world example where you might estimate multiplication Share your ideas with the class!
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