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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 207 · 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 79 × 93? (a) 72000 (b) 7200 (c) 720
  2. 2.Best estimate of 82 × 46? (a) 400 (b) 4000 (c) 40000
  3. 3.Best estimate of 23 × 76? (a) 1600 (b) 16000 (c) 160
  4. 4.Best estimate of 384 + 386? (a) 600 (b) 1000 (c) 800
  5. 5.Best estimate of 92 × 53? (a) 45000 (b) 4500 (c) 450
  6. 6.Best estimate of 556 + 195? (a) 600 (b) 800 (c) 1000
  7. 7.Best estimate of 856 + 453? (a) 1200 (b) 1600 (c) 1400
  8. 8.Best estimate of 81 × 67? (a) 5600 (b) 56000 (c) 560
  9. 9.Best estimate of 96 × 82? (a) 8000 (b) 80000 (c) 800
  10. 10.Best estimate of 162 + 343? (a) 300 (b) 700 (c) 500
  11. 11.Best estimate of 54 × 86? (a) 45000 (b) 450 (c) 4500
  12. 12.Best estimate of 69 × 56? (a) 420 (b) 4200 (c) 42000
  13. 13.Best estimate of 69 × 80? (a) 56000 (b) 560 (c) 5600
  14. 14.Best estimate of 738 + 267? (a) 1200 (b) 800 (c) 1000
  15. 15.Best estimate of 226 + 443? (a) 600 (b) 400 (c) 800
  16. 16.Best estimate of 58 × 79? (a) 48000 (b) 4800 (c) 480
  17. 17.Best estimate of 50 × 47? (a) 2500 (b) 25000 (c) 250
  18. 18.Best estimate of 588 + 149? (a) 900 (b) 700 (c) 500
  19. 19.Best estimate of 219 + 413? (a) 800 (b) 400 (c) 600
  20. 20.Best estimate of 362 + 769? (a) 1200 (b) 1400 (c) 1000
  21. 21.Best estimate of 52 × 96? (a) 50000 (b) 500 (c) 5000
  22. 22.Best estimate of 645 + 297? (a) 700 (b) 1100 (c) 900
  23. 23.Best estimate of 76 × 48? (a) 40000 (b) 400 (c) 4000
  24. 24.Best estimate of 91 × 92? (a) 81000 (b) 8100 (c) 810
  25. 25.Best estimate of 801 + 447? (a) 1200 (b) 1400 (c) 1000
  26. 26.Best estimate of 788 + 691? (a) 1500 (b) 1300 (c) 1700
  27. 27.Best estimate of 61 × 77? (a) 480 (b) 48000 (c) 4800
  28. 28.Best estimate of 97 × 36? (a) 40000 (b) 4000 (c) 400
  29. 29.Best estimate of 71 × 98? (a) 700 (b) 70000 (c) 7000
  30. 30.Best estimate of 76 × 82? (a) 6400 (b) 64000 (c) 640
  31. 31.Best estimate of 462 + 276? (a) 1000 (b) 800 (c) 600
  32. 32.Best estimate of 51 × 29? (a) 15000 (b) 150 (c) 1500
  33. 33.Best estimate of 19 × 78? (a) 16000 (b) 160 (c) 1600
  34. 34.Best estimate of 90 × 27? (a) 2700 (b) 27000 (c) 270
  35. 35.Best estimate of 60 × 69? (a) 4200 (b) 420 (c) 42000
  36. 36.Best estimate of 487 + 667? (a) 1400 (b) 1200 (c) 1000
  37. 37.Best estimate of 233 + 801? (a) 1200 (b) 800 (c) 1000
  38. 38.Best estimate of 16 × 18? (a) 40 (b) 4000 (c) 400
  39. 39.Best estimate of 880 + 451? (a) 1400 (b) 1600 (c) 1200
  40. 40.Best estimate of 720 + 436? (a) 900 (b) 1100 (c) 1300

Answer key

  1. 7200
  2. 4000
  3. 1600
  4. 800
  5. 4500
  6. 800
  7. 1400
  8. 5600
  9. 8000
  10. 500
  11. 4500
  12. 4200
  13. 5600
  14. 1000
  15. 600
  16. 4800
  17. 2500
  18. 700
  19. 600
  20. 1200
  21. 5000
  22. 900
  23. 4000
  24. 8100
  25. 1200
  26. 1500
  27. 4800
  28. 4000
  29. 7000
  30. 6400
  31. 800
  32. 1500
  33. 1600
  34. 2700
  35. 4200
  36. 1200
  37. 1000
  38. 400
  39. 1400
  40. 1100

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