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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 674 · 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 456 + 806? (a) 1100 (b) 1300 (c) 1500
  2. 2.Best estimate of 28 × 74? (a) 21000 (b) 2100 (c) 210
  3. 3.Best estimate of 76 × 74? (a) 560 (b) 5600 (c) 56000
  4. 4.Best estimate of 728 + 610? (a) 1300 (b) 1500 (c) 1100
  5. 5.Best estimate of 871 + 761? (a) 1900 (b) 1700 (c) 1500
  6. 6.Best estimate of 638 + 771? (a) 1400 (b) 1200 (c) 1600
  7. 7.Best estimate of 785 + 558? (a) 1200 (b) 1400 (c) 1600
  8. 8.Best estimate of 331 + 646? (a) 700 (b) 1100 (c) 900
  9. 9.Best estimate of 47 × 26? (a) 150 (b) 1500 (c) 15000
  10. 10.Best estimate of 17 × 60? (a) 120 (b) 12000 (c) 1200
  11. 11.Best estimate of 880 + 391? (a) 1100 (b) 1300 (c) 1500
  12. 12.Best estimate of 368 + 163? (a) 800 (b) 400 (c) 600
  13. 13.Best estimate of 767 + 734? (a) 1500 (b) 1300 (c) 1700
  14. 14.Best estimate of 545 + 821? (a) 1300 (b) 1500 (c) 1100
  15. 15.Best estimate of 23 × 20? (a) 40 (b) 400 (c) 4000
  16. 16.Best estimate of 615 + 137? (a) 500 (b) 700 (c) 900
  17. 17.Best estimate of 488 + 391? (a) 700 (b) 900 (c) 1100
  18. 18.Best estimate of 96 × 17? (a) 2000 (b) 200 (c) 20000
  19. 19.Best estimate of 62 × 20? (a) 120 (b) 12000 (c) 1200
  20. 20.Best estimate of 21 × 82? (a) 16000 (b) 1600 (c) 160
  21. 21.Best estimate of 76 × 73? (a) 560 (b) 5600 (c) 56000
  22. 22.Best estimate of 69 × 24? (a) 140 (b) 14000 (c) 1400
  23. 23.Best estimate of 81 × 84? (a) 64000 (b) 640 (c) 6400
  24. 24.Best estimate of 96 × 32? (a) 30000 (b) 300 (c) 3000
  25. 25.Best estimate of 217 + 295? (a) 500 (b) 700 (c) 300
  26. 26.Best estimate of 632 + 313? (a) 1100 (b) 700 (c) 900
  27. 27.Best estimate of 128 + 337? (a) 200 (b) 600 (c) 400
  28. 28.Best estimate of 34 × 44? (a) 1200 (b) 12000 (c) 120
  29. 29.Best estimate of 16 × 39? (a) 80 (b) 800 (c) 8000
  30. 30.Best estimate of 98 × 51? (a) 50000 (b) 5000 (c) 500
  31. 31.Best estimate of 308 + 424? (a) 900 (b) 500 (c) 700
  32. 32.Best estimate of 806 + 192? (a) 1000 (b) 800 (c) 1200
  33. 33.Best estimate of 240 + 684? (a) 900 (b) 1100 (c) 700
  34. 34.Best estimate of 267 + 723? (a) 1000 (b) 800 (c) 1200
  35. 35.Best estimate of 316 + 166? (a) 700 (b) 300 (c) 500
  36. 36.Best estimate of 446 + 782? (a) 1000 (b) 1400 (c) 1200
  37. 37.Best estimate of 46 × 91? (a) 4500 (b) 450 (c) 45000
  38. 38.Best estimate of 325 + 760? (a) 900 (b) 1300 (c) 1100
  39. 39.Best estimate of 399 + 378? (a) 800 (b) 600 (c) 1000
  40. 40.Best estimate of 639 + 536? (a) 1100 (b) 900 (c) 1300

Answer key

  1. 1300
  2. 2100
  3. 5600
  4. 1300
  5. 1700
  6. 1400
  7. 1400
  8. 900
  9. 1500
  10. 1200
  11. 1300
  12. 600
  13. 1500
  14. 1300
  15. 400
  16. 700
  17. 900
  18. 2000
  19. 1200
  20. 1600
  21. 5600
  22. 1400
  23. 6400
  24. 3000
  25. 500
  26. 900
  27. 400
  28. 1200
  29. 800
  30. 5000
  31. 700
  32. 1000
  33. 900
  34. 1000
  35. 500
  36. 1200
  37. 4500
  38. 1100
  39. 800
  40. 1100

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