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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 638 · 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 44 × 36? (a) 1600 (b) 16000 (c) 160
  2. 2.Best estimate of 18 × 52? (a) 10000 (b) 1000 (c) 100
  3. 3.Best estimate of 809 + 777? (a) 1600 (b) 1800 (c) 1400
  4. 4.Best estimate of 306 + 472? (a) 800 (b) 600 (c) 1000
  5. 5.Best estimate of 727 + 814? (a) 1700 (b) 1500 (c) 1300
  6. 6.Best estimate of 345 + 837? (a) 1100 (b) 1300 (c) 900
  7. 7.Best estimate of 20 × 29? (a) 6000 (b) 600 (c) 60
  8. 8.Best estimate of 360 + 466? (a) 900 (b) 1100 (c) 700
  9. 9.Best estimate of 322 + 582? (a) 700 (b) 1100 (c) 900
  10. 10.Best estimate of 34 × 28? (a) 900 (b) 9000 (c) 90
  11. 11.Best estimate of 44 × 18? (a) 80 (b) 800 (c) 8000
  12. 12.Best estimate of 94 × 66? (a) 63000 (b) 630 (c) 6300
  13. 13.Best estimate of 794 + 553? (a) 1400 (b) 1200 (c) 1600
  14. 14.Best estimate of 56 × 39? (a) 24000 (b) 2400 (c) 240
  15. 15.Best estimate of 24 × 43? (a) 80 (b) 8000 (c) 800
  16. 16.Best estimate of 638 + 175? (a) 800 (b) 1000 (c) 600
  17. 17.Best estimate of 44 × 26? (a) 12000 (b) 120 (c) 1200
  18. 18.Best estimate of 133 + 324? (a) 200 (b) 600 (c) 400
  19. 19.Best estimate of 46 × 57? (a) 300 (b) 30000 (c) 3000
  20. 20.Best estimate of 434 + 315? (a) 700 (b) 900 (c) 500
  21. 21.Best estimate of 599 + 507? (a) 1300 (b) 900 (c) 1100
  22. 22.Best estimate of 496 + 383? (a) 700 (b) 900 (c) 1100
  23. 23.Best estimate of 38 × 54? (a) 2000 (b) 200 (c) 20000
  24. 24.Best estimate of 563 + 544? (a) 1100 (b) 1300 (c) 900
  25. 25.Best estimate of 263 + 125? (a) 600 (b) 200 (c) 400
  26. 26.Best estimate of 876 + 718? (a) 1600 (b) 1400 (c) 1800
  27. 27.Best estimate of 237 + 281? (a) 500 (b) 300 (c) 700
  28. 28.Best estimate of 14 × 30? (a) 3000 (b) 300 (c) 30
  29. 29.Best estimate of 20 × 53? (a) 1000 (b) 100 (c) 10000
  30. 30.Best estimate of 40 × 36? (a) 1600 (b) 160 (c) 16000
  31. 31.Best estimate of 724 + 653? (a) 1600 (b) 1200 (c) 1400
  32. 32.Best estimate of 679 + 449? (a) 900 (b) 1100 (c) 1300
  33. 33.Best estimate of 354 + 681? (a) 1300 (b) 1100 (c) 900
  34. 34.Best estimate of 20 × 21? (a) 400 (b) 4000 (c) 40
  35. 35.Best estimate of 42 × 52? (a) 20000 (b) 200 (c) 2000
  36. 36.Best estimate of 70 × 16? (a) 14000 (b) 1400 (c) 140
  37. 37.Best estimate of 27 × 59? (a) 18000 (b) 1800 (c) 180
  38. 38.Best estimate of 40 × 64? (a) 24000 (b) 2400 (c) 240
  39. 39.Best estimate of 79 × 79? (a) 64000 (b) 640 (c) 6400
  40. 40.Best estimate of 17 × 17? (a) 40 (b) 400 (c) 4000

Answer key

  1. 1600
  2. 1000
  3. 1600
  4. 800
  5. 1500
  6. 1100
  7. 600
  8. 900
  9. 900
  10. 900
  11. 800
  12. 6300
  13. 1400
  14. 2400
  15. 800
  16. 800
  17. 1200
  18. 400
  19. 3000
  20. 700
  21. 1100
  22. 900
  23. 2000
  24. 1100
  25. 400
  26. 1600
  27. 500
  28. 300
  29. 1000
  30. 1600
  31. 1400
  32. 1100
  33. 1100
  34. 400
  35. 2000
  36. 1400
  37. 1800
  38. 2400
  39. 6400
  40. 400

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