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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 438 · 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 455 + 746? (a) 1000 (b) 1400 (c) 1200
  2. 2.Best estimate of 36 × 57? (a) 24000 (b) 240 (c) 2400
  3. 3.Best estimate of 700 + 579? (a) 1300 (b) 1500 (c) 1100
  4. 4.Best estimate of 83 × 87? (a) 7200 (b) 720 (c) 72000
  5. 5.Best estimate of 68 × 96? (a) 70000 (b) 7000 (c) 700
  6. 6.Best estimate of 178 + 702? (a) 900 (b) 1100 (c) 700
  7. 7.Best estimate of 29 × 42? (a) 12000 (b) 1200 (c) 120
  8. 8.Best estimate of 63 × 57? (a) 36000 (b) 3600 (c) 360
  9. 9.Best estimate of 27 × 28? (a) 900 (b) 90 (c) 9000
  10. 10.Best estimate of 354 + 579? (a) 1200 (b) 1000 (c) 800
  11. 11.Best estimate of 18 × 72? (a) 1400 (b) 140 (c) 14000
  12. 12.Best estimate of 30 × 44? (a) 12000 (b) 120 (c) 1200
  13. 13.Best estimate of 57 × 76? (a) 480 (b) 4800 (c) 48000
  14. 14.Best estimate of 51 × 32? (a) 150 (b) 1500 (c) 15000
  15. 15.Best estimate of 42 × 76? (a) 3200 (b) 32000 (c) 320
  16. 16.Best estimate of 58 × 76? (a) 48000 (b) 4800 (c) 480
  17. 17.Best estimate of 244 + 296? (a) 500 (b) 300 (c) 700
  18. 18.Best estimate of 251 + 364? (a) 700 (b) 900 (c) 500
  19. 19.Best estimate of 81 × 38? (a) 3200 (b) 320 (c) 32000
  20. 20.Best estimate of 69 × 63? (a) 4200 (b) 420 (c) 42000
  21. 21.Best estimate of 17 × 32? (a) 6000 (b) 600 (c) 60
  22. 22.Best estimate of 29 × 87? (a) 270 (b) 2700 (c) 27000
  23. 23.Best estimate of 190 + 793? (a) 1200 (b) 1000 (c) 800
  24. 24.Best estimate of 460 + 697? (a) 1400 (b) 1200 (c) 1000
  25. 25.Best estimate of 208 + 384? (a) 800 (b) 600 (c) 400
  26. 26.Best estimate of 536 + 725? (a) 1400 (b) 1200 (c) 1000
  27. 27.Best estimate of 61 × 16? (a) 120 (b) 12000 (c) 1200
  28. 28.Best estimate of 46 × 78? (a) 400 (b) 40000 (c) 4000
  29. 29.Best estimate of 446 + 138? (a) 700 (b) 500 (c) 300
  30. 30.Best estimate of 77 × 28? (a) 2400 (b) 24000 (c) 240
  31. 31.Best estimate of 14 × 89? (a) 90 (b) 9000 (c) 900
  32. 32.Best estimate of 63 × 26? (a) 1800 (b) 180 (c) 18000
  33. 33.Best estimate of 646 + 194? (a) 600 (b) 800 (c) 1000
  34. 34.Best estimate of 69 × 82? (a) 56000 (b) 5600 (c) 560
  35. 35.Best estimate of 569 + 566? (a) 1000 (b) 1400 (c) 1200
  36. 36.Best estimate of 74 × 57? (a) 42000 (b) 420 (c) 4200
  37. 37.Best estimate of 88 × 97? (a) 900 (b) 9000 (c) 90000
  38. 38.Best estimate of 56 × 67? (a) 4200 (b) 420 (c) 42000
  39. 39.Best estimate of 22 × 50? (a) 1000 (b) 10000 (c) 100
  40. 40.Best estimate of 29 × 31? (a) 900 (b) 9000 (c) 90

Answer key

  1. 1200
  2. 2400
  3. 1300
  4. 7200
  5. 7000
  6. 900
  7. 1200
  8. 3600
  9. 900
  10. 1000
  11. 1400
  12. 1200
  13. 4800
  14. 1500
  15. 3200
  16. 4800
  17. 500
  18. 700
  19. 3200
  20. 4200
  21. 600
  22. 2700
  23. 1000
  24. 1200
  25. 600
  26. 1200
  27. 1200
  28. 4000
  29. 500
  30. 2400
  31. 900
  32. 1800
  33. 800
  34. 5600
  35. 1200
  36. 4200
  37. 9000
  38. 4200
  39. 1000
  40. 900

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