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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 640 · 40 questions
TalentJR

How to do it in your head (Round, then work): Round each number: 2-digit numbers to the nearest ten, 3-digit numbers to the nearest hundred. Do the easy sum with the round numbers. Choose the option closest to your estimate.

NameDateTime takenScore ___ / 40
  1. 1.Best estimate of 20 × 16? (a) 400 (b) 40 (c) 4000
  2. 2.Best estimate of 458 + 489? (a) 1000 (b) 800 (c) 1200
  3. 3.Best estimate of 88 × 26? (a) 27000 (b) 270 (c) 2700
  4. 4.Best estimate of 36 × 43? (a) 160 (b) 1600 (c) 16000
  5. 5.Best estimate of 160 + 491? (a) 500 (b) 900 (c) 700
  6. 6.Best estimate of 422 + 358? (a) 1000 (b) 600 (c) 800
  7. 7.Best estimate of 42 × 81? (a) 3200 (b) 320 (c) 32000
  8. 8.Best estimate of 76 × 74? (a) 56000 (b) 5600 (c) 560
  9. 9.Best estimate of 22 × 46? (a) 1000 (b) 10000 (c) 100
  10. 10.Best estimate of 41 × 66? (a) 280 (b) 28000 (c) 2800
  11. 11.Best estimate of 229 + 688? (a) 1100 (b) 900 (c) 700
  12. 12.Best estimate of 129 + 789? (a) 700 (b) 1100 (c) 900
  13. 13.Best estimate of 641 + 144? (a) 500 (b) 700 (c) 900
  14. 14.Best estimate of 69 × 39? (a) 28000 (b) 280 (c) 2800
  15. 15.Best estimate of 57 × 41? (a) 24000 (b) 2400 (c) 240
  16. 16.Best estimate of 23 × 31? (a) 600 (b) 60 (c) 6000
  17. 17.Best estimate of 56 × 23? (a) 12000 (b) 120 (c) 1200
  18. 18.Best estimate of 53 × 69? (a) 35000 (b) 350 (c) 3500
  19. 19.Best estimate of 433 + 265? (a) 700 (b) 500 (c) 900
  20. 20.Best estimate of 36 × 22? (a) 800 (b) 8000 (c) 80
  21. 21.Best estimate of 860 + 644? (a) 1300 (b) 1500 (c) 1700
  22. 22.Best estimate of 751 + 548? (a) 1100 (b) 1300 (c) 1500
  23. 23.Best estimate of 310 + 605? (a) 1100 (b) 900 (c) 700
  24. 24.Best estimate of 445 + 774? (a) 1200 (b) 1400 (c) 1000
  25. 25.Best estimate of 46 × 56? (a) 300 (b) 3000 (c) 30000
  26. 26.Best estimate of 620 + 558? (a) 1200 (b) 1400 (c) 1000
  27. 27.Best estimate of 599 + 278? (a) 900 (b) 1100 (c) 700
  28. 28.Best estimate of 87 × 14? (a) 900 (b) 9000 (c) 90
  29. 29.Best estimate of 36 × 27? (a) 120 (b) 1200 (c) 12000
  30. 30.Best estimate of 67 × 72? (a) 49000 (b) 4900 (c) 490
  31. 31.Best estimate of 394 + 855? (a) 1500 (b) 1300 (c) 1100
  32. 32.Best estimate of 28 × 22? (a) 600 (b) 60 (c) 6000
  33. 33.Best estimate of 62 × 67? (a) 4200 (b) 420 (c) 42000
  34. 34.Best estimate of 713 + 160? (a) 700 (b) 900 (c) 1100
  35. 35.Best estimate of 878 + 727? (a) 1800 (b) 1400 (c) 1600
  36. 36.Best estimate of 267 + 129? (a) 200 (b) 600 (c) 400
  37. 37.Best estimate of 36 × 90? (a) 360 (b) 36000 (c) 3600
  38. 38.Best estimate of 46 × 39? (a) 2000 (b) 200 (c) 20000
  39. 39.Best estimate of 84 × 39? (a) 32000 (b) 320 (c) 3200
  40. 40.Best estimate of 279 + 278? (a) 800 (b) 600 (c) 400

Answer key

  1. 400
  2. 1000
  3. 2700
  4. 1600
  5. 700
  6. 800
  7. 3200
  8. 5600
  9. 1000
  10. 2800
  11. 900
  12. 900
  13. 700
  14. 2800
  15. 2400
  16. 600
  17. 1200
  18. 3500
  19. 700
  20. 800
  21. 1500
  22. 1300
  23. 900
  24. 1200
  25. 3000
  26. 1200
  27. 900
  28. 900
  29. 1200
  30. 4900
  31. 1300
  32. 600
  33. 4200
  34. 900
  35. 1600
  36. 400
  37. 3600
  38. 2000
  39. 3200
  40. 600

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