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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 395 · 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 18 × 23? (a) 40 (b) 400 (c) 4000
  2. 2.Best estimate of 30 × 93? (a) 2700 (b) 27000 (c) 270
  3. 3.Best estimate of 80 × 88? (a) 72000 (b) 7200 (c) 720
  4. 4.Best estimate of 528 + 870? (a) 1400 (b) 1200 (c) 1600
  5. 5.Best estimate of 764 + 799? (a) 1400 (b) 1800 (c) 1600
  6. 6.Best estimate of 13 × 40? (a) 4000 (b) 40 (c) 400
  7. 7.Best estimate of 24 × 80? (a) 16000 (b) 160 (c) 1600
  8. 8.Best estimate of 57 × 89? (a) 5400 (b) 54000 (c) 540
  9. 9.Best estimate of 471 + 778? (a) 1500 (b) 1100 (c) 1300
  10. 10.Best estimate of 611 + 574? (a) 1400 (b) 1200 (c) 1000
  11. 11.Best estimate of 329 + 860? (a) 1400 (b) 1200 (c) 1000
  12. 12.Best estimate of 395 + 513? (a) 1100 (b) 700 (c) 900
  13. 13.Best estimate of 369 + 677? (a) 1300 (b) 1100 (c) 900
  14. 14.Best estimate of 801 + 409? (a) 1400 (b) 1000 (c) 1200
  15. 15.Best estimate of 56 × 51? (a) 30000 (b) 300 (c) 3000
  16. 16.Best estimate of 18 × 63? (a) 1200 (b) 12000 (c) 120
  17. 17.Best estimate of 49 × 58? (a) 3000 (b) 30000 (c) 300
  18. 18.Best estimate of 72 × 81? (a) 560 (b) 5600 (c) 56000
  19. 19.Best estimate of 16 × 61? (a) 12000 (b) 120 (c) 1200
  20. 20.Best estimate of 153 + 175? (a) 200 (b) 600 (c) 400
  21. 21.Best estimate of 253 + 726? (a) 1000 (b) 1200 (c) 800
  22. 22.Best estimate of 50 × 43? (a) 200 (b) 2000 (c) 20000
  23. 23.Best estimate of 60 × 26? (a) 18000 (b) 1800 (c) 180
  24. 24.Best estimate of 96 × 79? (a) 8000 (b) 800 (c) 80000
  25. 25.Best estimate of 56 × 94? (a) 5400 (b) 540 (c) 54000
  26. 26.Best estimate of 767 + 252? (a) 1300 (b) 900 (c) 1100
  27. 27.Best estimate of 354 + 234? (a) 800 (b) 600 (c) 400
  28. 28.Best estimate of 772 + 375? (a) 1200 (b) 1400 (c) 1000
  29. 29.Best estimate of 19 × 34? (a) 600 (b) 60 (c) 6000
  30. 30.Best estimate of 20 × 97? (a) 2000 (b) 20000 (c) 200
  31. 31.Best estimate of 86 × 30? (a) 2700 (b) 27000 (c) 270
  32. 32.Best estimate of 259 + 869? (a) 1000 (b) 1200 (c) 1400
  33. 33.Best estimate of 548 + 271? (a) 1000 (b) 800 (c) 600
  34. 34.Best estimate of 431 + 607? (a) 800 (b) 1200 (c) 1000
  35. 35.Best estimate of 32 × 91? (a) 27000 (b) 2700 (c) 270
  36. 36.Best estimate of 775 + 568? (a) 1200 (b) 1600 (c) 1400
  37. 37.Best estimate of 96 × 59? (a) 600 (b) 60000 (c) 6000
  38. 38.Best estimate of 91 × 14? (a) 90 (b) 9000 (c) 900
  39. 39.Best estimate of 127 + 689? (a) 800 (b) 600 (c) 1000
  40. 40.Best estimate of 78 × 33? (a) 2400 (b) 240 (c) 24000

Answer key

  1. 400
  2. 2700
  3. 7200
  4. 1400
  5. 1600
  6. 400
  7. 1600
  8. 5400
  9. 1300
  10. 1200
  11. 1200
  12. 900
  13. 1100
  14. 1200
  15. 3000
  16. 1200
  17. 3000
  18. 5600
  19. 1200
  20. 400
  21. 1000
  22. 2000
  23. 1800
  24. 8000
  25. 5400
  26. 1100
  27. 600
  28. 1200
  29. 600
  30. 2000
  31. 2700
  32. 1200
  33. 800
  34. 1000
  35. 2700
  36. 1400
  37. 6000
  38. 900
  39. 800
  40. 2400

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