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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 148 · 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 761 + 732? (a) 1500 (b) 1700 (c) 1300
  2. 2.Best estimate of 326 + 756? (a) 1300 (b) 1100 (c) 900
  3. 3.Best estimate of 540 + 555? (a) 900 (b) 1100 (c) 1300
  4. 4.Best estimate of 22 × 71? (a) 1400 (b) 140 (c) 14000
  5. 5.Best estimate of 492 + 642? (a) 1300 (b) 900 (c) 1100
  6. 6.Best estimate of 211 + 661? (a) 1100 (b) 900 (c) 700
  7. 7.Best estimate of 57 × 50? (a) 30000 (b) 3000 (c) 300
  8. 8.Best estimate of 673 + 719? (a) 1200 (b) 1400 (c) 1600
  9. 9.Best estimate of 516 + 756? (a) 1500 (b) 1300 (c) 1100
  10. 10.Best estimate of 544 + 502? (a) 1000 (b) 1200 (c) 800
  11. 11.Best estimate of 37 × 16? (a) 80 (b) 800 (c) 8000
  12. 12.Best estimate of 259 + 625? (a) 900 (b) 1100 (c) 700
  13. 13.Best estimate of 76 × 70? (a) 5600 (b) 56000 (c) 560
  14. 14.Best estimate of 56 × 52? (a) 30000 (b) 3000 (c) 300
  15. 15.Best estimate of 763 + 827? (a) 1800 (b) 1400 (c) 1600
  16. 16.Best estimate of 52 × 78? (a) 4000 (b) 40000 (c) 400
  17. 17.Best estimate of 774 + 734? (a) 1700 (b) 1500 (c) 1300
  18. 18.Best estimate of 638 + 397? (a) 1000 (b) 1200 (c) 800
  19. 19.Best estimate of 40 × 68? (a) 2800 (b) 280 (c) 28000
  20. 20.Best estimate of 256 + 699? (a) 1200 (b) 800 (c) 1000
  21. 21.Best estimate of 479 + 616? (a) 1100 (b) 1300 (c) 900
  22. 22.Best estimate of 740 + 763? (a) 1700 (b) 1300 (c) 1500
  23. 23.Best estimate of 319 + 310? (a) 600 (b) 400 (c) 800
  24. 24.Best estimate of 31 × 74? (a) 210 (b) 2100 (c) 21000
  25. 25.Best estimate of 49 × 18? (a) 1000 (b) 10000 (c) 100
  26. 26.Best estimate of 412 + 602? (a) 1000 (b) 800 (c) 1200
  27. 27.Best estimate of 394 + 217? (a) 400 (b) 800 (c) 600
  28. 28.Best estimate of 132 + 273? (a) 200 (b) 600 (c) 400
  29. 29.Best estimate of 87 × 59? (a) 540 (b) 54000 (c) 5400
  30. 30.Best estimate of 23 × 31? (a) 6000 (b) 600 (c) 60
  31. 31.Best estimate of 79 × 66? (a) 5600 (b) 560 (c) 56000
  32. 32.Best estimate of 351 + 638? (a) 1200 (b) 800 (c) 1000
  33. 33.Best estimate of 22 × 90? (a) 1800 (b) 180 (c) 18000
  34. 34.Best estimate of 26 × 56? (a) 1800 (b) 18000 (c) 180
  35. 35.Best estimate of 525 + 577? (a) 900 (b) 1300 (c) 1100
  36. 36.Best estimate of 567 + 817? (a) 1400 (b) 1600 (c) 1200
  37. 37.Best estimate of 512 + 877? (a) 1400 (b) 1600 (c) 1200
  38. 38.Best estimate of 153 + 381? (a) 600 (b) 800 (c) 400
  39. 39.Best estimate of 78 × 33? (a) 24000 (b) 240 (c) 2400
  40. 40.Best estimate of 301 + 386? (a) 500 (b) 900 (c) 700

Answer key

  1. 1500
  2. 1100
  3. 1100
  4. 1400
  5. 1100
  6. 900
  7. 3000
  8. 1400
  9. 1300
  10. 1000
  11. 800
  12. 900
  13. 5600
  14. 3000
  15. 1600
  16. 4000
  17. 1500
  18. 1000
  19. 2800
  20. 1000
  21. 1100
  22. 1500
  23. 600
  24. 2100
  25. 1000
  26. 1000
  27. 600
  28. 400
  29. 5400
  30. 600
  31. 5600
  32. 1000
  33. 1800
  34. 1800
  35. 1100
  36. 1400
  37. 1400
  38. 600
  39. 2400
  40. 700

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