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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 112 · 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 34 × 82? (a) 240 (b) 2400 (c) 24000
  2. 2.Best estimate of 494 + 581? (a) 900 (b) 1100 (c) 1300
  3. 3.Best estimate of 653 + 378? (a) 900 (b) 1300 (c) 1100
  4. 4.Best estimate of 94 × 96? (a) 9000 (b) 900 (c) 90000
  5. 5.Best estimate of 42 × 58? (a) 2400 (b) 24000 (c) 240
  6. 6.Best estimate of 98 × 22? (a) 20000 (b) 200 (c) 2000
  7. 7.Best estimate of 44 × 96? (a) 4000 (b) 40000 (c) 400
  8. 8.Best estimate of 844 + 848? (a) 1600 (b) 1400 (c) 1800
  9. 9.Best estimate of 21 × 29? (a) 60 (b) 6000 (c) 600
  10. 10.Best estimate of 542 + 309? (a) 800 (b) 1000 (c) 600
  11. 11.Best estimate of 58 × 34? (a) 1800 (b) 180 (c) 18000
  12. 12.Best estimate of 137 + 237? (a) 500 (b) 100 (c) 300
  13. 13.Best estimate of 249 + 381? (a) 800 (b) 400 (c) 600
  14. 14.Best estimate of 62 × 16? (a) 1200 (b) 12000 (c) 120
  15. 15.Best estimate of 239 + 274? (a) 700 (b) 500 (c) 300
  16. 16.Best estimate of 66 × 73? (a) 49000 (b) 490 (c) 4900
  17. 17.Best estimate of 536 + 716? (a) 1200 (b) 1400 (c) 1000
  18. 18.Best estimate of 357 + 126? (a) 500 (b) 700 (c) 300
  19. 19.Best estimate of 353 + 281? (a) 900 (b) 500 (c) 700
  20. 20.Best estimate of 88 × 34? (a) 27000 (b) 270 (c) 2700
  21. 21.Best estimate of 24 × 70? (a) 140 (b) 14000 (c) 1400
  22. 22.Best estimate of 14 × 46? (a) 50 (b) 500 (c) 5000
  23. 23.Best estimate of 89 × 50? (a) 450 (b) 45000 (c) 4500
  24. 24.Best estimate of 16 × 66? (a) 14000 (b) 140 (c) 1400
  25. 25.Best estimate of 79 × 58? (a) 48000 (b) 4800 (c) 480
  26. 26.Best estimate of 98 × 37? (a) 4000 (b) 400 (c) 40000
  27. 27.Best estimate of 668 + 121? (a) 1000 (b) 800 (c) 600
  28. 28.Best estimate of 20 × 87? (a) 180 (b) 18000 (c) 1800
  29. 29.Best estimate of 94 × 19? (a) 180 (b) 1800 (c) 18000
  30. 30.Best estimate of 27 × 54? (a) 15000 (b) 1500 (c) 150
  31. 31.Best estimate of 43 × 40? (a) 1600 (b) 16000 (c) 160
  32. 32.Best estimate of 13 × 18? (a) 200 (b) 2000 (c) 20
  33. 33.Best estimate of 325 + 319? (a) 600 (b) 800 (c) 400
  34. 34.Best estimate of 630 + 814? (a) 1200 (b) 1600 (c) 1400
  35. 35.Best estimate of 632 + 367? (a) 1000 (b) 1200 (c) 800
  36. 36.Best estimate of 596 + 473? (a) 900 (b) 1300 (c) 1100
  37. 37.Best estimate of 28 × 82? (a) 240 (b) 2400 (c) 24000
  38. 38.Best estimate of 878 + 242? (a) 1100 (b) 1300 (c) 900
  39. 39.Best estimate of 23 × 79? (a) 1600 (b) 160 (c) 16000
  40. 40.Best estimate of 614 + 327? (a) 1100 (b) 900 (c) 700

Answer key

  1. 2400
  2. 1100
  3. 1100
  4. 9000
  5. 2400
  6. 2000
  7. 4000
  8. 1600
  9. 600
  10. 800
  11. 1800
  12. 300
  13. 600
  14. 1200
  15. 500
  16. 4900
  17. 1200
  18. 500
  19. 700
  20. 2700
  21. 1400
  22. 500
  23. 4500
  24. 1400
  25. 4800
  26. 4000
  27. 800
  28. 1800
  29. 1800
  30. 1500
  31. 1600
  32. 200
  33. 600
  34. 1400
  35. 1000
  36. 1100
  37. 2400
  38. 1100
  39. 1600
  40. 900

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