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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 730 · 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 864 + 532? (a) 1400 (b) 1600 (c) 1200
  2. 2.Best estimate of 18 × 76? (a) 160 (b) 16000 (c) 1600
  3. 3.Best estimate of 93 × 69? (a) 63000 (b) 6300 (c) 630
  4. 4.Best estimate of 129 + 205? (a) 300 (b) 500 (c) 100
  5. 5.Best estimate of 691 + 162? (a) 900 (b) 1100 (c) 700
  6. 6.Best estimate of 624 + 871? (a) 1700 (b) 1300 (c) 1500
  7. 7.Best estimate of 89 × 56? (a) 5400 (b) 54000 (c) 540
  8. 8.Best estimate of 16 × 73? (a) 1400 (b) 14000 (c) 140
  9. 9.Best estimate of 58 × 96? (a) 60000 (b) 6000 (c) 600
  10. 10.Best estimate of 37 × 36? (a) 16000 (b) 160 (c) 1600
  11. 11.Best estimate of 389 + 193? (a) 400 (b) 600 (c) 800
  12. 12.Best estimate of 799 + 808? (a) 1600 (b) 1800 (c) 1400
  13. 13.Best estimate of 28 × 24? (a) 60 (b) 600 (c) 6000
  14. 14.Best estimate of 529 + 379? (a) 1100 (b) 700 (c) 900
  15. 15.Best estimate of 68 × 58? (a) 42000 (b) 420 (c) 4200
  16. 16.Best estimate of 494 + 564? (a) 1100 (b) 1300 (c) 900
  17. 17.Best estimate of 734 + 810? (a) 1700 (b) 1500 (c) 1300
  18. 18.Best estimate of 416 + 174? (a) 400 (b) 600 (c) 800
  19. 19.Best estimate of 843 + 620? (a) 1600 (b) 1200 (c) 1400
  20. 20.Best estimate of 466 + 479? (a) 1200 (b) 800 (c) 1000
  21. 21.Best estimate of 86 × 63? (a) 5400 (b) 540 (c) 54000
  22. 22.Best estimate of 16 × 74? (a) 140 (b) 1400 (c) 14000
  23. 23.Best estimate of 12 × 49? (a) 5000 (b) 50 (c) 500
  24. 24.Best estimate of 295 + 326? (a) 600 (b) 400 (c) 800
  25. 25.Best estimate of 73 × 57? (a) 4200 (b) 420 (c) 42000
  26. 26.Best estimate of 22 × 17? (a) 400 (b) 40 (c) 4000
  27. 27.Best estimate of 34 × 40? (a) 12000 (b) 1200 (c) 120
  28. 28.Best estimate of 50 × 81? (a) 40000 (b) 400 (c) 4000
  29. 29.Best estimate of 221 + 586? (a) 800 (b) 600 (c) 1000
  30. 30.Best estimate of 60 × 34? (a) 18000 (b) 1800 (c) 180
  31. 31.Best estimate of 199 + 145? (a) 500 (b) 100 (c) 300
  32. 32.Best estimate of 14 × 50? (a) 500 (b) 50 (c) 5000
  33. 33.Best estimate of 578 + 838? (a) 1200 (b) 1600 (c) 1400
  34. 34.Best estimate of 80 × 89? (a) 72000 (b) 720 (c) 7200
  35. 35.Best estimate of 21 × 48? (a) 10000 (b) 100 (c) 1000
  36. 36.Best estimate of 74 × 89? (a) 6300 (b) 63000 (c) 630
  37. 37.Best estimate of 575 + 588? (a) 1200 (b) 1400 (c) 1000
  38. 38.Best estimate of 36 × 34? (a) 12000 (b) 1200 (c) 120
  39. 39.Best estimate of 469 + 705? (a) 1200 (b) 1400 (c) 1000
  40. 40.Best estimate of 50 × 64? (a) 300 (b) 3000 (c) 30000

Answer key

  1. 1400
  2. 1600
  3. 6300
  4. 300
  5. 900
  6. 1500
  7. 5400
  8. 1400
  9. 6000
  10. 1600
  11. 600
  12. 1600
  13. 600
  14. 900
  15. 4200
  16. 1100
  17. 1500
  18. 600
  19. 1400
  20. 1000
  21. 5400
  22. 1400
  23. 500
  24. 600
  25. 4200
  26. 400
  27. 1200
  28. 4000
  29. 800
  30. 1800
  31. 300
  32. 500
  33. 1400
  34. 7200
  35. 1000
  36. 6300
  37. 1200
  38. 1200
  39. 1200
  40. 3000

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