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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 134 · 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 14 × 34? (a) 3000 (b) 300 (c) 30
  2. 2.Best estimate of 50 × 14? (a) 50 (b) 500 (c) 5000
  3. 3.Best estimate of 498 + 532? (a) 1000 (b) 800 (c) 1200
  4. 4.Best estimate of 464 + 120? (a) 600 (b) 800 (c) 400
  5. 5.Best estimate of 273 + 424? (a) 700 (b) 500 (c) 900
  6. 6.Best estimate of 20 × 81? (a) 1600 (b) 16000 (c) 160
  7. 7.Best estimate of 395 + 264? (a) 700 (b) 500 (c) 900
  8. 8.Best estimate of 834 + 446? (a) 1000 (b) 1200 (c) 1400
  9. 9.Best estimate of 609 + 444? (a) 1200 (b) 800 (c) 1000
  10. 10.Best estimate of 784 + 837? (a) 1600 (b) 1800 (c) 1400
  11. 11.Best estimate of 621 + 585? (a) 1200 (b) 1000 (c) 1400
  12. 12.Best estimate of 56 × 56? (a) 36000 (b) 3600 (c) 360
  13. 13.Best estimate of 24 × 87? (a) 1800 (b) 180 (c) 18000
  14. 14.Best estimate of 692 + 306? (a) 1000 (b) 800 (c) 1200
  15. 15.Best estimate of 813 + 681? (a) 1300 (b) 1700 (c) 1500
  16. 16.Best estimate of 24 × 20? (a) 400 (b) 4000 (c) 40
  17. 17.Best estimate of 762 + 262? (a) 1100 (b) 900 (c) 1300
  18. 18.Best estimate of 586 + 626? (a) 1000 (b) 1200 (c) 1400
  19. 19.Best estimate of 727 + 766? (a) 1500 (b) 1700 (c) 1300
  20. 20.Best estimate of 638 + 745? (a) 1300 (b) 1100 (c) 1500
  21. 21.Best estimate of 256 + 393? (a) 900 (b) 700 (c) 500
  22. 22.Best estimate of 789 + 364? (a) 1000 (b) 1400 (c) 1200
  23. 23.Best estimate of 18 × 17? (a) 40 (b) 400 (c) 4000
  24. 24.Best estimate of 16 × 36? (a) 8000 (b) 800 (c) 80
  25. 25.Best estimate of 42 × 40? (a) 16000 (b) 160 (c) 1600
  26. 26.Best estimate of 70 × 59? (a) 42000 (b) 420 (c) 4200
  27. 27.Best estimate of 20 × 96? (a) 200 (b) 2000 (c) 20000
  28. 28.Best estimate of 36 × 43? (a) 16000 (b) 1600 (c) 160
  29. 29.Best estimate of 719 + 814? (a) 1300 (b) 1700 (c) 1500
  30. 30.Best estimate of 36 × 58? (a) 24000 (b) 2400 (c) 240
  31. 31.Best estimate of 76 × 70? (a) 5600 (b) 560 (c) 56000
  32. 32.Best estimate of 733 + 670? (a) 1600 (b) 1400 (c) 1200
  33. 33.Best estimate of 98 × 46? (a) 500 (b) 50000 (c) 5000
  34. 34.Best estimate of 511 + 325? (a) 1000 (b) 600 (c) 800
  35. 35.Best estimate of 39 × 84? (a) 3200 (b) 320 (c) 32000
  36. 36.Best estimate of 694 + 445? (a) 900 (b) 1300 (c) 1100
  37. 37.Best estimate of 16 × 53? (a) 100 (b) 1000 (c) 10000
  38. 38.Best estimate of 507 + 643? (a) 1100 (b) 900 (c) 1300
  39. 39.Best estimate of 81 × 12? (a) 800 (b) 8000 (c) 80
  40. 40.Best estimate of 73 × 92? (a) 63000 (b) 630 (c) 6300

Answer key

  1. 300
  2. 500
  3. 1000
  4. 600
  5. 700
  6. 1600
  7. 700
  8. 1200
  9. 1000
  10. 1600
  11. 1200
  12. 3600
  13. 1800
  14. 1000
  15. 1500
  16. 400
  17. 1100
  18. 1200
  19. 1500
  20. 1300
  21. 700
  22. 1200
  23. 400
  24. 800
  25. 1600
  26. 4200
  27. 2000
  28. 1600
  29. 1500
  30. 2400
  31. 5600
  32. 1400
  33. 5000
  34. 800
  35. 3200
  36. 1100
  37. 1000
  38. 1100
  39. 800
  40. 6300

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