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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 488 · 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 96 × 93? (a) 9000 (b) 90000 (c) 900
  2. 2.Best estimate of 218 + 262? (a) 700 (b) 500 (c) 300
  3. 3.Best estimate of 19 × 56? (a) 12000 (b) 120 (c) 1200
  4. 4.Best estimate of 448 + 306? (a) 700 (b) 500 (c) 900
  5. 5.Best estimate of 378 + 755? (a) 1400 (b) 1000 (c) 1200
  6. 6.Best estimate of 826 + 524? (a) 1500 (b) 1300 (c) 1100
  7. 7.Best estimate of 651 + 664? (a) 1400 (b) 1600 (c) 1200
  8. 8.Best estimate of 53 × 23? (a) 100 (b) 1000 (c) 10000
  9. 9.Best estimate of 728 + 364? (a) 900 (b) 1100 (c) 1300
  10. 10.Best estimate of 30 × 21? (a) 60 (b) 6000 (c) 600
  11. 11.Best estimate of 314 + 523? (a) 1000 (b) 800 (c) 600
  12. 12.Best estimate of 94 × 12? (a) 900 (b) 9000 (c) 90
  13. 13.Best estimate of 528 + 803? (a) 1300 (b) 1500 (c) 1100
  14. 14.Best estimate of 41 × 41? (a) 16000 (b) 1600 (c) 160
  15. 15.Best estimate of 21 × 16? (a) 4000 (b) 40 (c) 400
  16. 16.Best estimate of 56 × 32? (a) 18000 (b) 1800 (c) 180
  17. 17.Best estimate of 529 + 375? (a) 900 (b) 700 (c) 1100
  18. 18.Best estimate of 264 + 638? (a) 1100 (b) 900 (c) 700
  19. 19.Best estimate of 26 × 80? (a) 24000 (b) 240 (c) 2400
  20. 20.Best estimate of 90 × 82? (a) 7200 (b) 72000 (c) 720
  21. 21.Best estimate of 234 + 149? (a) 300 (b) 100 (c) 500
  22. 22.Best estimate of 726 + 652? (a) 1200 (b) 1400 (c) 1600
  23. 23.Best estimate of 96 × 14? (a) 10000 (b) 100 (c) 1000
  24. 24.Best estimate of 306 + 646? (a) 700 (b) 900 (c) 1100
  25. 25.Best estimate of 20 × 41? (a) 800 (b) 8000 (c) 80
  26. 26.Best estimate of 454 + 253? (a) 800 (b) 1000 (c) 600
  27. 27.Best estimate of 29 × 70? (a) 210 (b) 21000 (c) 2100
  28. 28.Best estimate of 21 × 39? (a) 80 (b) 800 (c) 8000
  29. 29.Best estimate of 12 × 31? (a) 300 (b) 30 (c) 3000
  30. 30.Best estimate of 214 + 606? (a) 800 (b) 600 (c) 1000
  31. 31.Best estimate of 386 + 143? (a) 500 (b) 300 (c) 700
  32. 32.Best estimate of 851 + 551? (a) 1300 (b) 1700 (c) 1500
  33. 33.Best estimate of 19 × 36? (a) 80 (b) 8000 (c) 800
  34. 34.Best estimate of 458 + 196? (a) 900 (b) 700 (c) 500
  35. 35.Best estimate of 576 + 703? (a) 1100 (b) 1300 (c) 1500
  36. 36.Best estimate of 44 × 46? (a) 2000 (b) 200 (c) 20000
  37. 37.Best estimate of 406 + 853? (a) 1100 (b) 1300 (c) 1500
  38. 38.Best estimate of 187 + 538? (a) 700 (b) 500 (c) 900
  39. 39.Best estimate of 16 × 21? (a) 4000 (b) 400 (c) 40
  40. 40.Best estimate of 94 × 93? (a) 810 (b) 8100 (c) 81000

Answer key

  1. 9000
  2. 500
  3. 1200
  4. 700
  5. 1200
  6. 1300
  7. 1400
  8. 1000
  9. 1100
  10. 600
  11. 800
  12. 900
  13. 1300
  14. 1600
  15. 400
  16. 1800
  17. 900
  18. 900
  19. 2400
  20. 7200
  21. 300
  22. 1400
  23. 1000
  24. 900
  25. 800
  26. 800
  27. 2100
  28. 800
  29. 300
  30. 800
  31. 500
  32. 1500
  33. 800
  34. 700
  35. 1300
  36. 2000
  37. 1300
  38. 700
  39. 400
  40. 8100

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