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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 845 · 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 28 × 18? (a) 600 (b) 60 (c) 6000
  2. 2.Best estimate of 14 × 87? (a) 9000 (b) 90 (c) 900
  3. 3.Best estimate of 74 × 86? (a) 6300 (b) 630 (c) 63000
  4. 4.Best estimate of 22 × 81? (a) 1600 (b) 16000 (c) 160
  5. 5.Best estimate of 282 + 135? (a) 400 (b) 200 (c) 600
  6. 6.Best estimate of 476 + 333? (a) 800 (b) 1000 (c) 600
  7. 7.Best estimate of 162 + 463? (a) 700 (b) 500 (c) 900
  8. 8.Best estimate of 577 + 717? (a) 1500 (b) 1300 (c) 1100
  9. 9.Best estimate of 271 + 164? (a) 500 (b) 300 (c) 700
  10. 10.Best estimate of 539 + 721? (a) 1200 (b) 1000 (c) 1400
  11. 11.Best estimate of 57 × 70? (a) 420 (b) 4200 (c) 42000
  12. 12.Best estimate of 593 + 791? (a) 1200 (b) 1400 (c) 1600
  13. 13.Best estimate of 220 + 439? (a) 600 (b) 400 (c) 800
  14. 14.Best estimate of 235 + 142? (a) 500 (b) 300 (c) 100
  15. 15.Best estimate of 659 + 349? (a) 1200 (b) 1000 (c) 800
  16. 16.Best estimate of 615 + 684? (a) 1100 (b) 1300 (c) 1500
  17. 17.Best estimate of 152 + 340? (a) 300 (b) 700 (c) 500
  18. 18.Best estimate of 616 + 625? (a) 1400 (b) 1000 (c) 1200
  19. 19.Best estimate of 534 + 717? (a) 1200 (b) 1400 (c) 1000
  20. 20.Best estimate of 80 × 58? (a) 480 (b) 4800 (c) 48000
  21. 21.Best estimate of 40 × 87? (a) 360 (b) 36000 (c) 3600
  22. 22.Best estimate of 73 × 82? (a) 56000 (b) 5600 (c) 560
  23. 23.Best estimate of 779 + 715? (a) 1700 (b) 1300 (c) 1500
  24. 24.Best estimate of 36 × 62? (a) 24000 (b) 2400 (c) 240
  25. 25.Best estimate of 82 × 49? (a) 4000 (b) 400 (c) 40000
  26. 26.Best estimate of 429 + 381? (a) 800 (b) 600 (c) 1000
  27. 27.Best estimate of 27 × 24? (a) 6000 (b) 600 (c) 60
  28. 28.Best estimate of 22 × 96? (a) 20000 (b) 2000 (c) 200
  29. 29.Best estimate of 16 × 80? (a) 16000 (b) 160 (c) 1600
  30. 30.Best estimate of 46 × 18? (a) 100 (b) 10000 (c) 1000
  31. 31.Best estimate of 22 × 86? (a) 180 (b) 18000 (c) 1800
  32. 32.Best estimate of 69 × 31? (a) 21000 (b) 2100 (c) 210
  33. 33.Best estimate of 64 × 51? (a) 3000 (b) 30000 (c) 300
  34. 34.Best estimate of 235 + 542? (a) 900 (b) 700 (c) 500
  35. 35.Best estimate of 192 + 694? (a) 1100 (b) 700 (c) 900
  36. 36.Best estimate of 322 + 680? (a) 800 (b) 1200 (c) 1000
  37. 37.Best estimate of 864 + 718? (a) 1800 (b) 1600 (c) 1400
  38. 38.Best estimate of 98 × 36? (a) 4000 (b) 40000 (c) 400
  39. 39.Best estimate of 78 × 60? (a) 4800 (b) 48000 (c) 480
  40. 40.Best estimate of 534 + 510? (a) 1000 (b) 800 (c) 1200

Answer key

  1. 600
  2. 900
  3. 6300
  4. 1600
  5. 400
  6. 800
  7. 700
  8. 1300
  9. 500
  10. 1200
  11. 4200
  12. 1400
  13. 600
  14. 300
  15. 1000
  16. 1300
  17. 500
  18. 1200
  19. 1200
  20. 4800
  21. 3600
  22. 5600
  23. 1500
  24. 2400
  25. 4000
  26. 800
  27. 600
  28. 2000
  29. 1600
  30. 1000
  31. 1800
  32. 2100
  33. 3000
  34. 700
  35. 900
  36. 1000
  37. 1600
  38. 4000
  39. 4800
  40. 1000

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