Using Estimation to Check Addition Answers | Reasonableness

🎓 Estimation – Year 3 (ACARA Code : AC9M3N05)
🎯Focus:
– Learn how to use estimation to check if addition answers make sense.

Key Ideas (Quick Guide)

https://youtu.be/85JYBxmpg4g

Try these after watching the video:

❓Question 1: Round 48 + 52 to estimate

✅ Answer: Rounding $48 + 52$ 48+52 to the nearest 10 gives $50 + 50 = 100$ 50+50=100, which is an accurate estimate.

❓Question 2: Is 63 + 38 ≈ 100?

✅ Answer: Yes, $63 + 38 \approx 100$ 63+38≈100 is a good estimate because rounding to the nearest 10 results in $60 + 40 = 100$ 60+40=100.

❓Question 3: Which is better: nearest 10 or 100 for 412 + 189?

✅ Answer: 412+189, rounding to the nearest 10 is better because it provides a more precise estimate than rounding to the nearest 100.

❓Question 4: Estimate 74 + 26

✅ Answer: Rounding $74 + 26$ 74+26 to the nearest 10 gives $70 + 30 = 100$ 70+30=100.

❓Question 5: Why do we estimate before checking?

✅ Answer: We estimate before performing exact calculations to quickly gauge if an answer is reasonable and to identify potential errors.

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