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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 498 · 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 74 × 87? (a) 6300 (b) 63000 (c) 630
  2. 2.Best estimate of 41 × 78? (a) 32000 (b) 3200 (c) 320
  3. 3.Best estimate of 523 + 781? (a) 1500 (b) 1100 (c) 1300
  4. 4.Best estimate of 27 × 62? (a) 18000 (b) 1800 (c) 180
  5. 5.Best estimate of 235 + 555? (a) 600 (b) 1000 (c) 800
  6. 6.Best estimate of 187 + 325? (a) 700 (b) 500 (c) 300
  7. 7.Best estimate of 13 × 51? (a) 500 (b) 5000 (c) 50
  8. 8.Best estimate of 54 × 73? (a) 350 (b) 35000 (c) 3500
  9. 9.Best estimate of 838 + 271? (a) 1300 (b) 1100 (c) 900
  10. 10.Best estimate of 46 × 96? (a) 50000 (b) 500 (c) 5000
  11. 11.Best estimate of 624 + 245? (a) 1000 (b) 800 (c) 600
  12. 12.Best estimate of 279 + 289? (a) 800 (b) 400 (c) 600
  13. 13.Best estimate of 251 + 826? (a) 1100 (b) 1300 (c) 900
  14. 14.Best estimate of 569 + 484? (a) 1300 (b) 900 (c) 1100
  15. 15.Best estimate of 52 × 23? (a) 100 (b) 10000 (c) 1000
  16. 16.Best estimate of 26 × 57? (a) 1800 (b) 180 (c) 18000
  17. 17.Best estimate of 34 × 56? (a) 18000 (b) 1800 (c) 180
  18. 18.Best estimate of 70 × 67? (a) 4900 (b) 49000 (c) 490
  19. 19.Best estimate of 384 + 765? (a) 1200 (b) 1000 (c) 1400
  20. 20.Best estimate of 67 × 64? (a) 42000 (b) 420 (c) 4200
  21. 21.Best estimate of 24 × 59? (a) 12000 (b) 1200 (c) 120
  22. 22.Best estimate of 128 + 248? (a) 100 (b) 500 (c) 300
  23. 23.Best estimate of 377 + 444? (a) 600 (b) 1000 (c) 800
  24. 24.Best estimate of 749 + 664? (a) 1400 (b) 1600 (c) 1200
  25. 25.Best estimate of 46 × 38? (a) 20000 (b) 200 (c) 2000
  26. 26.Best estimate of 39 × 23? (a) 80 (b) 800 (c) 8000
  27. 27.Best estimate of 599 + 176? (a) 600 (b) 1000 (c) 800
  28. 28.Best estimate of 72 × 30? (a) 21000 (b) 210 (c) 2100
  29. 29.Best estimate of 283 + 131? (a) 400 (b) 600 (c) 200
  30. 30.Best estimate of 87 × 86? (a) 810 (b) 81000 (c) 8100
  31. 31.Best estimate of 16 × 49? (a) 100 (b) 10000 (c) 1000
  32. 32.Best estimate of 695 + 190? (a) 1100 (b) 700 (c) 900
  33. 33.Best estimate of 82 × 97? (a) 8000 (b) 800 (c) 80000
  34. 34.Best estimate of 16 × 46? (a) 100 (b) 1000 (c) 10000
  35. 35.Best estimate of 60 × 19? (a) 12000 (b) 1200 (c) 120
  36. 36.Best estimate of 36 × 69? (a) 2800 (b) 28000 (c) 280
  37. 37.Best estimate of 27 × 53? (a) 15000 (b) 1500 (c) 150
  38. 38.Best estimate of 122 + 163? (a) 300 (b) 500 (c) 100
  39. 39.Best estimate of 69 × 77? (a) 56000 (b) 560 (c) 5600
  40. 40.Best estimate of 79 × 42? (a) 3200 (b) 320 (c) 32000

Answer key

  1. 6300
  2. 3200
  3. 1300
  4. 1800
  5. 800
  6. 500
  7. 500
  8. 3500
  9. 1100
  10. 5000
  11. 800
  12. 600
  13. 1100
  14. 1100
  15. 1000
  16. 1800
  17. 1800
  18. 4900
  19. 1200
  20. 4200
  21. 1200
  22. 300
  23. 800
  24. 1400
  25. 2000
  26. 800
  27. 800
  28. 2100
  29. 400
  30. 8100
  31. 1000
  32. 900
  33. 8000
  34. 1000
  35. 1200
  36. 2800
  37. 1500
  38. 300
  39. 5600
  40. 3200

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