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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 49 · 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 36 × 73? (a) 280 (b) 2800 (c) 28000
  2. 2.Best estimate of 47 × 97? (a) 500 (b) 5000 (c) 50000
  3. 3.Best estimate of 72 × 46? (a) 350 (b) 3500 (c) 35000
  4. 4.Best estimate of 342 + 151? (a) 700 (b) 500 (c) 300
  5. 5.Best estimate of 32 × 80? (a) 2400 (b) 240 (c) 24000
  6. 6.Best estimate of 324 + 759? (a) 900 (b) 1300 (c) 1100
  7. 7.Best estimate of 56 × 70? (a) 420 (b) 4200 (c) 42000
  8. 8.Best estimate of 87 × 44? (a) 36000 (b) 3600 (c) 360
  9. 9.Best estimate of 225 + 238? (a) 400 (b) 600 (c) 200
  10. 10.Best estimate of 40 × 76? (a) 320 (b) 32000 (c) 3200
  11. 11.Best estimate of 29 × 14? (a) 3000 (b) 30 (c) 300
  12. 12.Best estimate of 16 × 66? (a) 14000 (b) 140 (c) 1400
  13. 13.Best estimate of 356 + 791? (a) 1200 (b) 1400 (c) 1000
  14. 14.Best estimate of 367 + 347? (a) 900 (b) 500 (c) 700
  15. 15.Best estimate of 24 × 49? (a) 10000 (b) 1000 (c) 100
  16. 16.Best estimate of 380 + 827? (a) 1400 (b) 1000 (c) 1200
  17. 17.Best estimate of 36 × 97? (a) 4000 (b) 40000 (c) 400
  18. 18.Best estimate of 41 × 30? (a) 120 (b) 1200 (c) 12000
  19. 19.Best estimate of 89 × 43? (a) 3600 (b) 36000 (c) 360
  20. 20.Best estimate of 363 + 463? (a) 900 (b) 700 (c) 1100
  21. 21.Best estimate of 51 × 16? (a) 1000 (b) 100 (c) 10000
  22. 22.Best estimate of 14 × 12? (a) 100 (b) 1000 (c) 10
  23. 23.Best estimate of 865 + 839? (a) 1500 (b) 1700 (c) 1900
  24. 24.Best estimate of 72 × 59? (a) 420 (b) 42000 (c) 4200
  25. 25.Best estimate of 94 × 61? (a) 5400 (b) 540 (c) 54000
  26. 26.Best estimate of 351 + 236? (a) 800 (b) 400 (c) 600
  27. 27.Best estimate of 53 × 16? (a) 100 (b) 10000 (c) 1000
  28. 28.Best estimate of 838 + 141? (a) 1100 (b) 700 (c) 900
  29. 29.Best estimate of 69 × 76? (a) 5600 (b) 56000 (c) 560
  30. 30.Best estimate of 362 + 416? (a) 1000 (b) 800 (c) 600
  31. 31.Best estimate of 492 + 430? (a) 900 (b) 700 (c) 1100
  32. 32.Best estimate of 18 × 37? (a) 80 (b) 8000 (c) 800
  33. 33.Best estimate of 34 × 12? (a) 300 (b) 3000 (c) 30
  34. 34.Best estimate of 28 × 13? (a) 3000 (b) 300 (c) 30
  35. 35.Best estimate of 54 × 78? (a) 4000 (b) 40000 (c) 400
  36. 36.Best estimate of 258 + 224? (a) 500 (b) 300 (c) 700
  37. 37.Best estimate of 48 × 36? (a) 2000 (b) 20000 (c) 200
  38. 38.Best estimate of 71 × 98? (a) 7000 (b) 700 (c) 70000
  39. 39.Best estimate of 64 × 28? (a) 18000 (b) 1800 (c) 180
  40. 40.Best estimate of 21 × 80? (a) 1600 (b) 16000 (c) 160

Answer key

  1. 2800
  2. 5000
  3. 3500
  4. 500
  5. 2400
  6. 1100
  7. 4200
  8. 3600
  9. 400
  10. 3200
  11. 300
  12. 1400
  13. 1200
  14. 700
  15. 1000
  16. 1200
  17. 4000
  18. 1200
  19. 3600
  20. 900
  21. 1000
  22. 100
  23. 1700
  24. 4200
  25. 5400
  26. 600
  27. 1000
  28. 900
  29. 5600
  30. 800
  31. 900
  32. 800
  33. 300
  34. 300
  35. 4000
  36. 500
  37. 2000
  38. 7000
  39. 1800
  40. 1600

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