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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 873 · 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 154 + 280? (a) 300 (b) 500 (c) 700
  2. 2.Best estimate of 83 × 26? (a) 2400 (b) 240 (c) 24000
  3. 3.Best estimate of 94 × 70? (a) 630 (b) 63000 (c) 6300
  4. 4.Best estimate of 56 × 62? (a) 36000 (b) 3600 (c) 360
  5. 5.Best estimate of 286 + 225? (a) 300 (b) 500 (c) 700
  6. 6.Best estimate of 144 + 333? (a) 200 (b) 400 (c) 600
  7. 7.Best estimate of 36 × 97? (a) 4000 (b) 40000 (c) 400
  8. 8.Best estimate of 184 + 438? (a) 400 (b) 600 (c) 800
  9. 9.Best estimate of 41 × 37? (a) 160 (b) 1600 (c) 16000
  10. 10.Best estimate of 97 × 38? (a) 40000 (b) 400 (c) 4000
  11. 11.Best estimate of 51 × 49? (a) 250 (b) 2500 (c) 25000
  12. 12.Best estimate of 86 × 78? (a) 72000 (b) 720 (c) 7200
  13. 13.Best estimate of 538 + 249? (a) 900 (b) 500 (c) 700
  14. 14.Best estimate of 601 + 445? (a) 800 (b) 1200 (c) 1000
  15. 15.Best estimate of 785 + 651? (a) 1500 (b) 1700 (c) 1300
  16. 16.Best estimate of 564 + 843? (a) 1600 (b) 1400 (c) 1200
  17. 17.Best estimate of 80 × 54? (a) 400 (b) 4000 (c) 40000
  18. 18.Best estimate of 738 + 227? (a) 900 (b) 1100 (c) 700
  19. 19.Best estimate of 47 × 87? (a) 4500 (b) 450 (c) 45000
  20. 20.Best estimate of 26 × 78? (a) 2400 (b) 240 (c) 24000
  21. 21.Best estimate of 14 × 36? (a) 4000 (b) 40 (c) 400
  22. 22.Best estimate of 328 + 529? (a) 600 (b) 1000 (c) 800
  23. 23.Best estimate of 86 × 96? (a) 90000 (b) 9000 (c) 900
  24. 24.Best estimate of 39 × 50? (a) 2000 (b) 20000 (c) 200
  25. 25.Best estimate of 187 + 361? (a) 600 (b) 800 (c) 400
  26. 26.Best estimate of 171 + 269? (a) 700 (b) 500 (c) 300
  27. 27.Best estimate of 83 × 66? (a) 56000 (b) 5600 (c) 560
  28. 28.Best estimate of 264 + 555? (a) 1100 (b) 700 (c) 900
  29. 29.Best estimate of 164 + 718? (a) 1100 (b) 700 (c) 900
  30. 30.Best estimate of 17 × 91? (a) 18000 (b) 1800 (c) 180
  31. 31.Best estimate of 534 + 199? (a) 700 (b) 500 (c) 900
  32. 32.Best estimate of 31 × 54? (a) 15000 (b) 1500 (c) 150
  33. 33.Best estimate of 92 × 49? (a) 4500 (b) 45000 (c) 450
  34. 34.Best estimate of 22 × 32? (a) 60 (b) 600 (c) 6000
  35. 35.Best estimate of 285 + 778? (a) 1100 (b) 900 (c) 1300
  36. 36.Best estimate of 878 + 779? (a) 1900 (b) 1500 (c) 1700
  37. 37.Best estimate of 90 × 56? (a) 540 (b) 54000 (c) 5400
  38. 38.Best estimate of 54 × 93? (a) 4500 (b) 45000 (c) 450
  39. 39.Best estimate of 615 + 383? (a) 1200 (b) 800 (c) 1000
  40. 40.Best estimate of 48 × 36? (a) 2000 (b) 20000 (c) 200

Answer key

  1. 500
  2. 2400
  3. 6300
  4. 3600
  5. 500
  6. 400
  7. 4000
  8. 600
  9. 1600
  10. 4000
  11. 2500
  12. 7200
  13. 700
  14. 1000
  15. 1500
  16. 1400
  17. 4000
  18. 900
  19. 4500
  20. 2400
  21. 400
  22. 800
  23. 9000
  24. 2000
  25. 600
  26. 500
  27. 5600
  28. 900
  29. 900
  30. 1800
  31. 700
  32. 1500
  33. 4500
  34. 600
  35. 1100
  36. 1700
  37. 5400
  38. 4500
  39. 1000
  40. 2000

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