Estimating Division Worksheet - Use Mental Math to Estimate Quotients.

Let's solve the Estimating Division Worksheet using mental math to estimate the quotients. The goal is to round numbers to make division easier, then compute an approximate answer.

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🔹 Section 1

#### 1. $ 108 \div 9 $
- Think: $ 9 \times 12 = 108 $
- So, $ 108 \div 9 = 12 $
✔ Exact: 12

#### 2. $ 120 \div 2 $
- $ 120 \div 2 = 60 $
✔ Exact: 60

#### 3. $ 365 \div 5 $
- Round 365 to 360 (close and divisible by 5)
- $ 360 \div 5 = 72 $
- So, estimate: 72

#### 4. $ 630 \div 7 $
- $ 7 \times 90 = 630 $
- So, $ 630 \div 7 = 90 $
✔ Exact: 90

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🔹 Section 2

#### 5. $ 2550 \div 5 $
- $ 2550 \div 5 $: Half of 2550 is 1275 → but better:
- $ 2500 \div 5 = 500 $, so $ 2550 \div 5 \approx 510 $
✔ Estimate: 510

#### 6. $ 1600 \div 8 $
- $ 1600 \div 8 = 200 $
✔ Exact: 200

#### 7. $ 3638 \div 2 $
- $ 3600 \div 2 = 1800 $, and $ 38 \div 2 = 19 $
- So, $ 3638 \div 2 = 1819 $
✔ Exact: 1819

#### 8. $ 99 \div 11 $
- $ 11 \times 9 = 99 $
- So, $ 99 \div 11 = 9 $
✔ Exact: 9

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🔹 Section 3

#### 9. $ 3600 \div 90 $
- Simplify: $ 3600 \div 90 = 360 \div 9 = 40 $
✔ Exact: 40

#### 10. $ 20 \div 4 $
- $ 20 \div 4 = 5 $
✔ Exact: 5

#### 11. $ 209 \div 19 $
- Estimate: $ 200 \div 20 = 10 $
- But 19 is close to 20, and 209 is a bit more than 200
- Try $ 19 \times 10 = 190 $, $ 19 \times 11 = 209 $
- So, $ 209 \div 19 = 11 $
✔ Exact: 11

#### 12. $ 1800 \div 15 $
- $ 15 \times 120 = 1800 $
- So, $ 1800 \div 15 = 120 $
✔ Exact: 120

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🔹 Section 4

#### 13. $ 72 \div 9 $
- $ 9 \times 8 = 72 $
- So, $ 72 \div 9 = 8 $
✔ Exact: 8

#### 14. $ 1300 \div 12 $
- Estimate: $ 1200 \div 12 = 100 $, $ 1300 - 1200 = 100 $
- $ 100 \div 12 \approx 8.3 $
- So total ≈ $ 100 + 8.3 = 108.3 $
- Or: $ 1300 \div 12 \approx 108 $
✔ Estimate: 108

#### 15. $ 240 \div 20 $
- $ 240 \div 20 = 12 $
✔ Exact: 12

#### 16. $ 19200 \div 16 $
- Simplify: $ 19200 \div 16 $
- $ 192 \div 16 = 12 $, so $ 19200 \div 16 = 1200 $
✔ Exact: 1200

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✔ Final Answers (Estimated or Exact):

| Problem | Answer |
|--------|--------|
| 1. $108 \div 9$ | 12 |
| 2. $120 \div 2$ | 60 |
| 3. $365 \div 5$ | 72 |
| 4. $630 \div 7$ | 90 |
| 5. $2550 \div 5$ | 510 |
| 6. $1600 \div 8$ | 200 |
| 7. $3638 \div 2$ | 1819 |
| 8. $99 \div 11$ | 9 |
| 9. $3600 \div 90$ | 40 |
| 10. $20 \div 4$ | 5 |
| 11. $209 \div 19$ | 11 |
| 12. $1800 \div 15$ | 120 |
| 13. $72 \div 9$ | 8 |
| 14. $1300 \div 12$ | 108 |
| 15. $240 \div 20$ | 12 |
| 16. $19200 \div 16$ | 1200 |

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💡 Tips for Mental Estimation:

- Round numbers to nearby multiples.
- Use friendly numbers (like 10, 5, 100).
- For large numbers, simplify by dividing both numbers by 10 or 100 first.
- Know your multiplication facts — they help!

This worksheet helps build number sense and confidence in estimating division problems quickly.

Let me know if you'd like a printable version or a step-by-step guide for each!