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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 252 · 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 155 + 228? (a) 600 (b) 400 (c) 200
  2. 2.Best estimate of 215 + 153? (a) 600 (b) 400 (c) 200
  3. 3.Best estimate of 90 × 51? (a) 45000 (b) 450 (c) 4500
  4. 4.Best estimate of 22 × 24? (a) 400 (b) 40 (c) 4000
  5. 5.Best estimate of 49 × 26? (a) 15000 (b) 1500 (c) 150
  6. 6.Best estimate of 447 + 179? (a) 400 (b) 800 (c) 600
  7. 7.Best estimate of 836 + 527? (a) 1100 (b) 1300 (c) 1500
  8. 8.Best estimate of 777 + 501? (a) 1300 (b) 1100 (c) 1500
  9. 9.Best estimate of 479 + 708? (a) 1000 (b) 1200 (c) 1400
  10. 10.Best estimate of 47 × 36? (a) 2000 (b) 20000 (c) 200
  11. 11.Best estimate of 614 + 337? (a) 900 (b) 700 (c) 1100
  12. 12.Best estimate of 48 × 44? (a) 20000 (b) 200 (c) 2000
  13. 13.Best estimate of 16 × 78? (a) 160 (b) 16000 (c) 1600
  14. 14.Best estimate of 66 × 97? (a) 70000 (b) 7000 (c) 700
  15. 15.Best estimate of 584 + 666? (a) 1500 (b) 1100 (c) 1300
  16. 16.Best estimate of 182 + 317? (a) 700 (b) 300 (c) 500
  17. 17.Best estimate of 13 × 57? (a) 6000 (b) 600 (c) 60
  18. 18.Best estimate of 688 + 336? (a) 1000 (b) 1200 (c) 800
  19. 19.Best estimate of 27 × 16? (a) 60 (b) 6000 (c) 600
  20. 20.Best estimate of 726 + 528? (a) 1200 (b) 1400 (c) 1000
  21. 21.Best estimate of 43 × 59? (a) 24000 (b) 240 (c) 2400
  22. 22.Best estimate of 147 + 386? (a) 700 (b) 500 (c) 300
  23. 23.Best estimate of 72 × 31? (a) 21000 (b) 210 (c) 2100
  24. 24.Best estimate of 81 × 72? (a) 560 (b) 56000 (c) 5600
  25. 25.Best estimate of 344 + 426? (a) 700 (b) 900 (c) 500
  26. 26.Best estimate of 20 × 36? (a) 80 (b) 800 (c) 8000
  27. 27.Best estimate of 23 × 56? (a) 1200 (b) 12000 (c) 120
  28. 28.Best estimate of 36 × 31? (a) 12000 (b) 120 (c) 1200
  29. 29.Best estimate of 256 + 343? (a) 800 (b) 600 (c) 400
  30. 30.Best estimate of 498 + 175? (a) 500 (b) 700 (c) 900
  31. 31.Best estimate of 16 × 80? (a) 1600 (b) 160 (c) 16000
  32. 32.Best estimate of 36 × 84? (a) 32000 (b) 320 (c) 3200
  33. 33.Best estimate of 86 × 16? (a) 180 (b) 1800 (c) 18000
  34. 34.Best estimate of 21 × 92? (a) 1800 (b) 18000 (c) 180
  35. 35.Best estimate of 41 × 16? (a) 800 (b) 8000 (c) 80
  36. 36.Best estimate of 880 + 187? (a) 1100 (b) 1300 (c) 900
  37. 37.Best estimate of 77 × 97? (a) 8000 (b) 800 (c) 80000
  38. 38.Best estimate of 98 × 66? (a) 7000 (b) 70000 (c) 700
  39. 39.Best estimate of 528 + 490? (a) 1200 (b) 800 (c) 1000
  40. 40.Best estimate of 277 + 587? (a) 700 (b) 1100 (c) 900

Answer key

  1. 400
  2. 400
  3. 4500
  4. 400
  5. 1500
  6. 600
  7. 1300
  8. 1300
  9. 1200
  10. 2000
  11. 900
  12. 2000
  13. 1600
  14. 7000
  15. 1300
  16. 500
  17. 600
  18. 1000
  19. 600
  20. 1200
  21. 2400
  22. 500
  23. 2100
  24. 5600
  25. 700
  26. 800
  27. 1200
  28. 1200
  29. 600
  30. 700
  31. 1600
  32. 3200
  33. 1800
  34. 1800
  35. 800
  36. 1100
  37. 8000
  38. 7000
  39. 1000
  40. 900

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