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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 810 · 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 229 + 263? (a) 700 (b) 500 (c) 300
  2. 2.Best estimate of 724 + 224? (a) 1100 (b) 700 (c) 900
  3. 3.Best estimate of 274 + 136? (a) 200 (b) 400 (c) 600
  4. 4.Best estimate of 638 + 787? (a) 1400 (b) 1600 (c) 1200
  5. 5.Best estimate of 654 + 674? (a) 1600 (b) 1200 (c) 1400
  6. 6.Best estimate of 54 × 73? (a) 35000 (b) 3500 (c) 350
  7. 7.Best estimate of 63 × 19? (a) 120 (b) 12000 (c) 1200
  8. 8.Best estimate of 78 × 21? (a) 16000 (b) 160 (c) 1600
  9. 9.Best estimate of 47 × 16? (a) 1000 (b) 100 (c) 10000
  10. 10.Best estimate of 79 × 13? (a) 8000 (b) 800 (c) 80
  11. 11.Best estimate of 34 × 70? (a) 210 (b) 21000 (c) 2100
  12. 12.Best estimate of 91 × 96? (a) 900 (b) 90000 (c) 9000
  13. 13.Best estimate of 72 × 17? (a) 1400 (b) 14000 (c) 140
  14. 14.Best estimate of 97 × 73? (a) 70000 (b) 7000 (c) 700
  15. 15.Best estimate of 96 × 36? (a) 4000 (b) 400 (c) 40000
  16. 16.Best estimate of 862 + 203? (a) 1100 (b) 1300 (c) 900
  17. 17.Best estimate of 32 × 74? (a) 2100 (b) 21000 (c) 210
  18. 18.Best estimate of 48 × 98? (a) 500 (b) 50000 (c) 5000
  19. 19.Best estimate of 861 + 125? (a) 1000 (b) 800 (c) 1200
  20. 20.Best estimate of 36 × 18? (a) 800 (b) 80 (c) 8000
  21. 21.Best estimate of 646 + 321? (a) 1100 (b) 700 (c) 900
  22. 22.Best estimate of 63 × 51? (a) 3000 (b) 300 (c) 30000
  23. 23.Best estimate of 758 + 796? (a) 1600 (b) 1800 (c) 1400
  24. 24.Best estimate of 551 + 204? (a) 1000 (b) 600 (c) 800
  25. 25.Best estimate of 56 × 82? (a) 480 (b) 4800 (c) 48000
  26. 26.Best estimate of 69 × 48? (a) 3500 (b) 350 (c) 35000
  27. 27.Best estimate of 246 + 256? (a) 700 (b) 300 (c) 500
  28. 28.Best estimate of 89 × 76? (a) 72000 (b) 720 (c) 7200
  29. 29.Best estimate of 46 × 91? (a) 450 (b) 4500 (c) 45000
  30. 30.Best estimate of 20 × 23? (a) 400 (b) 4000 (c) 40
  31. 31.Best estimate of 72 × 22? (a) 140 (b) 14000 (c) 1400
  32. 32.Best estimate of 561 + 511? (a) 900 (b) 1300 (c) 1100
  33. 33.Best estimate of 769 + 567? (a) 1200 (b) 1400 (c) 1600
  34. 34.Best estimate of 71 × 24? (a) 1400 (b) 140 (c) 14000
  35. 35.Best estimate of 16 × 69? (a) 14000 (b) 1400 (c) 140
  36. 36.Best estimate of 515 + 557? (a) 900 (b) 1100 (c) 1300
  37. 37.Best estimate of 68 × 82? (a) 56000 (b) 5600 (c) 560
  38. 38.Best estimate of 54 × 28? (a) 15000 (b) 150 (c) 1500
  39. 39.Best estimate of 76 × 96? (a) 8000 (b) 80000 (c) 800
  40. 40.Best estimate of 80 × 73? (a) 5600 (b) 56000 (c) 560

Answer key

  1. 500
  2. 900
  3. 400
  4. 1400
  5. 1400
  6. 3500
  7. 1200
  8. 1600
  9. 1000
  10. 800
  11. 2100
  12. 9000
  13. 1400
  14. 7000
  15. 4000
  16. 1100
  17. 2100
  18. 5000
  19. 1000
  20. 800
  21. 900
  22. 3000
  23. 1600
  24. 800
  25. 4800
  26. 3500
  27. 500
  28. 7200
  29. 4500
  30. 400
  31. 1400
  32. 1100
  33. 1400
  34. 1400
  35. 1400
  36. 1100
  37. 5600
  38. 1500
  39. 8000
  40. 5600

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