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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 868 · 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 53 × 84? (a) 400 (b) 4000 (c) 40000
  2. 2.Best estimate of 61 × 56? (a) 360 (b) 36000 (c) 3600
  3. 3.Best estimate of 638 + 302? (a) 700 (b) 1100 (c) 900
  4. 4.Best estimate of 98 × 81? (a) 80000 (b) 800 (c) 8000
  5. 5.Best estimate of 76 × 63? (a) 480 (b) 48000 (c) 4800
  6. 6.Best estimate of 776 + 227? (a) 1200 (b) 1000 (c) 800
  7. 7.Best estimate of 591 + 335? (a) 1100 (b) 900 (c) 700
  8. 8.Best estimate of 66 × 12? (a) 7000 (b) 700 (c) 70
  9. 9.Best estimate of 78 × 42? (a) 3200 (b) 320 (c) 32000
  10. 10.Best estimate of 820 + 139? (a) 700 (b) 1100 (c) 900
  11. 11.Best estimate of 771 + 269? (a) 1300 (b) 900 (c) 1100
  12. 12.Best estimate of 42 × 61? (a) 2400 (b) 240 (c) 24000
  13. 13.Best estimate of 298 + 322? (a) 600 (b) 800 (c) 400
  14. 14.Best estimate of 36 × 14? (a) 4000 (b) 400 (c) 40
  15. 15.Best estimate of 401 + 379? (a) 1000 (b) 800 (c) 600
  16. 16.Best estimate of 253 + 513? (a) 1000 (b) 600 (c) 800
  17. 17.Best estimate of 830 + 829? (a) 1400 (b) 1600 (c) 1800
  18. 18.Best estimate of 341 + 240? (a) 500 (b) 300 (c) 700
  19. 19.Best estimate of 143 + 744? (a) 600 (b) 800 (c) 1000
  20. 20.Best estimate of 266 + 406? (a) 700 (b) 900 (c) 500
  21. 21.Best estimate of 40 × 17? (a) 800 (b) 8000 (c) 80
  22. 22.Best estimate of 31 × 71? (a) 2100 (b) 210 (c) 21000
  23. 23.Best estimate of 572 + 749? (a) 1500 (b) 1100 (c) 1300
  24. 24.Best estimate of 719 + 451? (a) 1200 (b) 1400 (c) 1000
  25. 25.Best estimate of 69 × 97? (a) 7000 (b) 70000 (c) 700
  26. 26.Best estimate of 684 + 430? (a) 900 (b) 1300 (c) 1100
  27. 27.Best estimate of 451 + 597? (a) 1100 (b) 900 (c) 1300
  28. 28.Best estimate of 757 + 624? (a) 1600 (b) 1400 (c) 1200
  29. 29.Best estimate of 710 + 841? (a) 1700 (b) 1500 (c) 1300
  30. 30.Best estimate of 507 + 805? (a) 1500 (b) 1300 (c) 1100
  31. 31.Best estimate of 32 × 97? (a) 300 (b) 30000 (c) 3000
  32. 32.Best estimate of 52 × 12? (a) 500 (b) 5000 (c) 50
  33. 33.Best estimate of 47 × 21? (a) 10000 (b) 1000 (c) 100
  34. 34.Best estimate of 532 + 212? (a) 900 (b) 700 (c) 500
  35. 35.Best estimate of 497 + 140? (a) 600 (b) 800 (c) 400
  36. 36.Best estimate of 98 × 48? (a) 5000 (b) 500 (c) 50000
  37. 37.Best estimate of 38 × 16? (a) 800 (b) 8000 (c) 80
  38. 38.Best estimate of 796 + 725? (a) 1500 (b) 1300 (c) 1700
  39. 39.Best estimate of 98 × 61? (a) 6000 (b) 60000 (c) 600
  40. 40.Best estimate of 352 + 309? (a) 900 (b) 500 (c) 700

Answer key

  1. 4000
  2. 3600
  3. 900
  4. 8000
  5. 4800
  6. 1000
  7. 900
  8. 700
  9. 3200
  10. 900
  11. 1100
  12. 2400
  13. 600
  14. 400
  15. 800
  16. 800
  17. 1600
  18. 500
  19. 800
  20. 700
  21. 800
  22. 2100
  23. 1300
  24. 1200
  25. 7000
  26. 1100
  27. 1100
  28. 1400
  29. 1500
  30. 1300
  31. 3000
  32. 500
  33. 1000
  34. 700
  35. 600
  36. 5000
  37. 800
  38. 1500
  39. 6000
  40. 700

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