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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 84 · 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 605 + 837? (a) 1600 (b) 1400 (c) 1200
  2. 2.Best estimate of 411 + 778? (a) 1400 (b) 1200 (c) 1000
  3. 3.Best estimate of 71 × 40? (a) 280 (b) 28000 (c) 2800
  4. 4.Best estimate of 543 + 161? (a) 700 (b) 900 (c) 500
  5. 5.Best estimate of 57 × 57? (a) 360 (b) 3600 (c) 36000
  6. 6.Best estimate of 515 + 570? (a) 900 (b) 1100 (c) 1300
  7. 7.Best estimate of 34 × 18? (a) 6000 (b) 60 (c) 600
  8. 8.Best estimate of 14 × 44? (a) 400 (b) 4000 (c) 40
  9. 9.Best estimate of 233 + 500? (a) 700 (b) 500 (c) 900
  10. 10.Best estimate of 152 + 770? (a) 1000 (b) 1200 (c) 800
  11. 11.Best estimate of 369 + 308? (a) 700 (b) 900 (c) 500
  12. 12.Best estimate of 193 + 132? (a) 100 (b) 300 (c) 500
  13. 13.Best estimate of 90 × 82? (a) 72000 (b) 720 (c) 7200
  14. 14.Best estimate of 280 + 401? (a) 700 (b) 900 (c) 500
  15. 15.Best estimate of 30 × 50? (a) 15000 (b) 150 (c) 1500
  16. 16.Best estimate of 217 + 130? (a) 500 (b) 300 (c) 100
  17. 17.Best estimate of 299 + 361? (a) 700 (b) 500 (c) 900
  18. 18.Best estimate of 66 × 21? (a) 140 (b) 1400 (c) 14000
  19. 19.Best estimate of 28 × 52? (a) 1500 (b) 150 (c) 15000
  20. 20.Best estimate of 38 × 80? (a) 32000 (b) 3200 (c) 320
  21. 21.Best estimate of 739 + 257? (a) 1200 (b) 800 (c) 1000
  22. 22.Best estimate of 66 × 86? (a) 6300 (b) 63000 (c) 630
  23. 23.Best estimate of 156 + 246? (a) 200 (b) 600 (c) 400
  24. 24.Best estimate of 29 × 39? (a) 120 (b) 12000 (c) 1200
  25. 25.Best estimate of 62 × 27? (a) 18000 (b) 1800 (c) 180
  26. 26.Best estimate of 197 + 547? (a) 900 (b) 500 (c) 700
  27. 27.Best estimate of 172 + 383? (a) 600 (b) 800 (c) 400
  28. 28.Best estimate of 855 + 553? (a) 1700 (b) 1500 (c) 1300
  29. 29.Best estimate of 215 + 148? (a) 500 (b) 100 (c) 300
  30. 30.Best estimate of 214 + 388? (a) 600 (b) 800 (c) 400
  31. 31.Best estimate of 43 × 64? (a) 24000 (b) 2400 (c) 240
  32. 32.Best estimate of 72 × 30? (a) 2100 (b) 21000 (c) 210
  33. 33.Best estimate of 374 + 579? (a) 1200 (b) 1000 (c) 800
  34. 34.Best estimate of 97 × 23? (a) 2000 (b) 20000 (c) 200
  35. 35.Best estimate of 90 × 63? (a) 54000 (b) 540 (c) 5400
  36. 36.Best estimate of 541 + 637? (a) 900 (b) 1300 (c) 1100
  37. 37.Best estimate of 33 × 36? (a) 12000 (b) 1200 (c) 120
  38. 38.Best estimate of 23 × 58? (a) 120 (b) 12000 (c) 1200
  39. 39.Best estimate of 12 × 16? (a) 20 (b) 200 (c) 2000
  40. 40.Best estimate of 87 × 33? (a) 2700 (b) 270 (c) 27000

Answer key

  1. 1400
  2. 1200
  3. 2800
  4. 700
  5. 3600
  6. 1100
  7. 600
  8. 400
  9. 700
  10. 1000
  11. 700
  12. 300
  13. 7200
  14. 700
  15. 1500
  16. 300
  17. 700
  18. 1400
  19. 1500
  20. 3200
  21. 1000
  22. 6300
  23. 400
  24. 1200
  25. 1800
  26. 700
  27. 600
  28. 1500
  29. 300
  30. 600
  31. 2400
  32. 2100
  33. 1000
  34. 2000
  35. 5400
  36. 1100
  37. 1200
  38. 1200
  39. 200
  40. 2700

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