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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 769 · 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 23 × 16? (a) 4000 (b) 400 (c) 40
  2. 2.Best estimate of 72 × 73? (a) 4900 (b) 49000 (c) 490
  3. 3.Best estimate of 799 + 767? (a) 1400 (b) 1800 (c) 1600
  4. 4.Best estimate of 402 + 134? (a) 300 (b) 500 (c) 700
  5. 5.Best estimate of 32 × 18? (a) 60 (b) 600 (c) 6000
  6. 6.Best estimate of 331 + 314? (a) 800 (b) 600 (c) 400
  7. 7.Best estimate of 72 × 77? (a) 56000 (b) 5600 (c) 560
  8. 8.Best estimate of 372 + 442? (a) 600 (b) 1000 (c) 800
  9. 9.Best estimate of 18 × 48? (a) 10000 (b) 100 (c) 1000
  10. 10.Best estimate of 96 × 86? (a) 9000 (b) 90000 (c) 900
  11. 11.Best estimate of 12 × 22? (a) 2000 (b) 200 (c) 20
  12. 12.Best estimate of 492 + 139? (a) 800 (b) 600 (c) 400
  13. 13.Best estimate of 42 × 89? (a) 360 (b) 3600 (c) 36000
  14. 14.Best estimate of 156 + 318? (a) 500 (b) 700 (c) 300
  15. 15.Best estimate of 60 × 84? (a) 480 (b) 48000 (c) 4800
  16. 16.Best estimate of 476 + 416? (a) 900 (b) 700 (c) 1100
  17. 17.Best estimate of 778 + 772? (a) 1800 (b) 1600 (c) 1400
  18. 18.Best estimate of 605 + 199? (a) 800 (b) 1000 (c) 600
  19. 19.Best estimate of 41 × 57? (a) 24000 (b) 2400 (c) 240
  20. 20.Best estimate of 16 × 97? (a) 2000 (b) 20000 (c) 200
  21. 21.Best estimate of 31 × 90? (a) 270 (b) 2700 (c) 27000
  22. 22.Best estimate of 96 × 46? (a) 500 (b) 5000 (c) 50000
  23. 23.Best estimate of 84 × 21? (a) 16000 (b) 1600 (c) 160
  24. 24.Best estimate of 97 × 26? (a) 3000 (b) 30000 (c) 300
  25. 25.Best estimate of 443 + 154? (a) 800 (b) 400 (c) 600
  26. 26.Best estimate of 66 × 58? (a) 4200 (b) 42000 (c) 420
  27. 27.Best estimate of 80 × 58? (a) 4800 (b) 48000 (c) 480
  28. 28.Best estimate of 62 × 40? (a) 2400 (b) 24000 (c) 240
  29. 29.Best estimate of 88 × 58? (a) 5400 (b) 540 (c) 54000
  30. 30.Best estimate of 52 × 36? (a) 200 (b) 2000 (c) 20000
  31. 31.Best estimate of 22 × 62? (a) 12000 (b) 1200 (c) 120
  32. 32.Best estimate of 83 × 41? (a) 320 (b) 3200 (c) 32000
  33. 33.Best estimate of 37 × 66? (a) 2800 (b) 280 (c) 28000
  34. 34.Best estimate of 80 × 81? (a) 640 (b) 6400 (c) 64000
  35. 35.Best estimate of 271 + 314? (a) 400 (b) 800 (c) 600
  36. 36.Best estimate of 477 + 386? (a) 1100 (b) 700 (c) 900
  37. 37.Best estimate of 388 + 359? (a) 600 (b) 800 (c) 1000
  38. 38.Best estimate of 77 × 26? (a) 240 (b) 24000 (c) 2400
  39. 39.Best estimate of 863 + 181? (a) 1300 (b) 900 (c) 1100
  40. 40.Best estimate of 24 × 40? (a) 800 (b) 8000 (c) 80

Answer key

  1. 400
  2. 4900
  3. 1600
  4. 500
  5. 600
  6. 600
  7. 5600
  8. 800
  9. 1000
  10. 9000
  11. 200
  12. 600
  13. 3600
  14. 500
  15. 4800
  16. 900
  17. 1600
  18. 800
  19. 2400
  20. 2000
  21. 2700
  22. 5000
  23. 1600
  24. 3000
  25. 600
  26. 4200
  27. 4800
  28. 2400
  29. 5400
  30. 2000
  31. 1200
  32. 3200
  33. 2800
  34. 6400
  35. 600
  36. 900
  37. 800
  38. 2400
  39. 1100
  40. 800

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