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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 105 · 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 56 × 22? (a) 120 (b) 1200 (c) 12000
  2. 2.Best estimate of 36 × 28? (a) 120 (b) 1200 (c) 12000
  3. 3.Best estimate of 63 × 77? (a) 48000 (b) 480 (c) 4800
  4. 4.Best estimate of 747 + 124? (a) 800 (b) 1000 (c) 600
  5. 5.Best estimate of 130 + 624? (a) 900 (b) 700 (c) 500
  6. 6.Best estimate of 23 × 59? (a) 120 (b) 1200 (c) 12000
  7. 7.Best estimate of 43 × 76? (a) 3200 (b) 320 (c) 32000
  8. 8.Best estimate of 653 + 289? (a) 800 (b) 1200 (c) 1000
  9. 9.Best estimate of 76 × 37? (a) 3200 (b) 32000 (c) 320
  10. 10.Best estimate of 69 × 66? (a) 49000 (b) 490 (c) 4900
  11. 11.Best estimate of 93 × 76? (a) 720 (b) 72000 (c) 7200
  12. 12.Best estimate of 63 × 29? (a) 180 (b) 1800 (c) 18000
  13. 13.Best estimate of 33 × 54? (a) 150 (b) 15000 (c) 1500
  14. 14.Best estimate of 26 × 81? (a) 2400 (b) 24000 (c) 240
  15. 15.Best estimate of 387 + 610? (a) 1200 (b) 1000 (c) 800
  16. 16.Best estimate of 96 × 66? (a) 700 (b) 7000 (c) 70000
  17. 17.Best estimate of 643 + 172? (a) 600 (b) 800 (c) 1000
  18. 18.Best estimate of 631 + 262? (a) 1100 (b) 700 (c) 900
  19. 19.Best estimate of 21 × 16? (a) 40 (b) 4000 (c) 400
  20. 20.Best estimate of 41 × 36? (a) 16000 (b) 1600 (c) 160
  21. 21.Best estimate of 59 × 78? (a) 48000 (b) 480 (c) 4800
  22. 22.Best estimate of 493 + 287? (a) 600 (b) 1000 (c) 800
  23. 23.Best estimate of 96 × 81? (a) 80000 (b) 8000 (c) 800
  24. 24.Best estimate of 62 × 36? (a) 240 (b) 24000 (c) 2400
  25. 25.Best estimate of 264 + 426? (a) 900 (b) 500 (c) 700
  26. 26.Best estimate of 653 + 453? (a) 1200 (b) 1000 (c) 1400
  27. 27.Best estimate of 20 × 42? (a) 8000 (b) 80 (c) 800
  28. 28.Best estimate of 27 × 26? (a) 9000 (b) 90 (c) 900
  29. 29.Best estimate of 434 + 790? (a) 1400 (b) 1000 (c) 1200
  30. 30.Best estimate of 255 + 797? (a) 1300 (b) 900 (c) 1100
  31. 31.Best estimate of 54 × 73? (a) 350 (b) 3500 (c) 35000
  32. 32.Best estimate of 32 × 30? (a) 9000 (b) 90 (c) 900
  33. 33.Best estimate of 674 + 151? (a) 700 (b) 1100 (c) 900
  34. 34.Best estimate of 481 + 482? (a) 1000 (b) 800 (c) 1200
  35. 35.Best estimate of 28 × 26? (a) 9000 (b) 900 (c) 90
  36. 36.Best estimate of 249 + 411? (a) 600 (b) 400 (c) 800
  37. 37.Best estimate of 324 + 183? (a) 300 (b) 500 (c) 700
  38. 38.Best estimate of 56 × 92? (a) 5400 (b) 540 (c) 54000
  39. 39.Best estimate of 855 + 482? (a) 1400 (b) 1600 (c) 1200
  40. 40.Best estimate of 254 + 221? (a) 700 (b) 300 (c) 500

Answer key

  1. 1200
  2. 1200
  3. 4800
  4. 800
  5. 700
  6. 1200
  7. 3200
  8. 1000
  9. 3200
  10. 4900
  11. 7200
  12. 1800
  13. 1500
  14. 2400
  15. 1000
  16. 7000
  17. 800
  18. 900
  19. 400
  20. 1600
  21. 4800
  22. 800
  23. 8000
  24. 2400
  25. 700
  26. 1200
  27. 800
  28. 900
  29. 1200
  30. 1100
  31. 3500
  32. 900
  33. 900
  34. 1000
  35. 900
  36. 600
  37. 500
  38. 5400
  39. 1400
  40. 500

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