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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 938 · 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 × 41? (a) 800 (b) 80 (c) 8000
  2. 2.Best estimate of 80 × 28? (a) 240 (b) 2400 (c) 24000
  3. 3.Best estimate of 592 + 760? (a) 1400 (b) 1600 (c) 1200
  4. 4.Best estimate of 16 × 86? (a) 18000 (b) 180 (c) 1800
  5. 5.Best estimate of 76 × 28? (a) 2400 (b) 240 (c) 24000
  6. 6.Best estimate of 260 + 160? (a) 700 (b) 300 (c) 500
  7. 7.Best estimate of 419 + 204? (a) 600 (b) 400 (c) 800
  8. 8.Best estimate of 41 × 91? (a) 360 (b) 36000 (c) 3600
  9. 9.Best estimate of 71 × 28? (a) 21000 (b) 210 (c) 2100
  10. 10.Best estimate of 30 × 51? (a) 15000 (b) 1500 (c) 150
  11. 11.Best estimate of 21 × 59? (a) 1200 (b) 120 (c) 12000
  12. 12.Best estimate of 31 × 18? (a) 600 (b) 60 (c) 6000
  13. 13.Best estimate of 201 + 163? (a) 600 (b) 400 (c) 200
  14. 14.Best estimate of 196 + 411? (a) 400 (b) 800 (c) 600
  15. 15.Best estimate of 682 + 206? (a) 700 (b) 1100 (c) 900
  16. 16.Best estimate of 62 × 96? (a) 60000 (b) 600 (c) 6000
  17. 17.Best estimate of 91 × 26? (a) 27000 (b) 270 (c) 2700
  18. 18.Best estimate of 51 × 93? (a) 450 (b) 45000 (c) 4500
  19. 19.Best estimate of 78 × 53? (a) 400 (b) 40000 (c) 4000
  20. 20.Best estimate of 646 + 210? (a) 1000 (b) 800 (c) 600
  21. 21.Best estimate of 71 × 23? (a) 1400 (b) 140 (c) 14000
  22. 22.Best estimate of 96 × 76? (a) 800 (b) 80000 (c) 8000
  23. 23.Best estimate of 319 + 681? (a) 800 (b) 1200 (c) 1000
  24. 24.Best estimate of 326 + 359? (a) 700 (b) 900 (c) 500
  25. 25.Best estimate of 141 + 274? (a) 400 (b) 200 (c) 600
  26. 26.Best estimate of 152 + 413? (a) 800 (b) 600 (c) 400
  27. 27.Best estimate of 770 + 147? (a) 700 (b) 900 (c) 1100
  28. 28.Best estimate of 270 + 206? (a) 300 (b) 700 (c) 500
  29. 29.Best estimate of 581 + 781? (a) 1600 (b) 1200 (c) 1400
  30. 30.Best estimate of 19 × 56? (a) 120 (b) 1200 (c) 12000
  31. 31.Best estimate of 211 + 307? (a) 500 (b) 700 (c) 300
  32. 32.Best estimate of 17 × 46? (a) 10000 (b) 100 (c) 1000
  33. 33.Best estimate of 33 × 89? (a) 27000 (b) 2700 (c) 270
  34. 34.Best estimate of 215 + 345? (a) 500 (b) 700 (c) 300
  35. 35.Best estimate of 660 + 591? (a) 1500 (b) 1300 (c) 1100
  36. 36.Best estimate of 83 × 86? (a) 7200 (b) 720 (c) 72000
  37. 37.Best estimate of 37 × 52? (a) 2000 (b) 200 (c) 20000
  38. 38.Best estimate of 782 + 512? (a) 1300 (b) 1100 (c) 1500
  39. 39.Best estimate of 91 × 51? (a) 4500 (b) 450 (c) 45000
  40. 40.Best estimate of 28 × 41? (a) 120 (b) 12000 (c) 1200

Answer key

  1. 800
  2. 2400
  3. 1400
  4. 1800
  5. 2400
  6. 500
  7. 600
  8. 3600
  9. 2100
  10. 1500
  11. 1200
  12. 600
  13. 400
  14. 600
  15. 900
  16. 6000
  17. 2700
  18. 4500
  19. 4000
  20. 800
  21. 1400
  22. 8000
  23. 1000
  24. 700
  25. 400
  26. 600
  27. 900
  28. 500
  29. 1400
  30. 1200
  31. 500
  32. 1000
  33. 2700
  34. 500
  35. 1300
  36. 7200
  37. 2000
  38. 1300
  39. 4500
  40. 1200

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