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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 39 · 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 66 × 88? (a) 6300 (b) 63000 (c) 630
  2. 2.Best estimate of 867 + 241? (a) 1300 (b) 900 (c) 1100
  3. 3.Best estimate of 347 + 300? (a) 800 (b) 600 (c) 400
  4. 4.Best estimate of 136 + 865? (a) 800 (b) 1200 (c) 1000
  5. 5.Best estimate of 174 + 464? (a) 500 (b) 700 (c) 900
  6. 6.Best estimate of 847 + 772? (a) 1800 (b) 1600 (c) 1400
  7. 7.Best estimate of 90 × 80? (a) 72000 (b) 720 (c) 7200
  8. 8.Best estimate of 34 × 43? (a) 120 (b) 12000 (c) 1200
  9. 9.Best estimate of 36 × 81? (a) 32000 (b) 320 (c) 3200
  10. 10.Best estimate of 52 × 87? (a) 450 (b) 45000 (c) 4500
  11. 11.Best estimate of 470 + 785? (a) 1500 (b) 1100 (c) 1300
  12. 12.Best estimate of 565 + 491? (a) 1100 (b) 1300 (c) 900
  13. 13.Best estimate of 60 × 87? (a) 5400 (b) 540 (c) 54000
  14. 14.Best estimate of 86 × 30? (a) 2700 (b) 270 (c) 27000
  15. 15.Best estimate of 96 × 41? (a) 400 (b) 40000 (c) 4000
  16. 16.Best estimate of 693 + 255? (a) 800 (b) 1200 (c) 1000
  17. 17.Best estimate of 503 + 397? (a) 900 (b) 700 (c) 1100
  18. 18.Best estimate of 79 × 94? (a) 7200 (b) 72000 (c) 720
  19. 19.Best estimate of 59 × 72? (a) 420 (b) 42000 (c) 4200
  20. 20.Best estimate of 89 × 67? (a) 6300 (b) 630 (c) 63000
  21. 21.Best estimate of 337 + 531? (a) 800 (b) 1000 (c) 600
  22. 22.Best estimate of 382 + 230? (a) 800 (b) 600 (c) 400
  23. 23.Best estimate of 877 + 529? (a) 1200 (b) 1600 (c) 1400
  24. 24.Best estimate of 16 × 53? (a) 10000 (b) 100 (c) 1000
  25. 25.Best estimate of 67 × 26? (a) 210 (b) 21000 (c) 2100
  26. 26.Best estimate of 62 × 36? (a) 240 (b) 2400 (c) 24000
  27. 27.Best estimate of 26 × 91? (a) 2700 (b) 270 (c) 27000
  28. 28.Best estimate of 158 + 298? (a) 300 (b) 500 (c) 700
  29. 29.Best estimate of 92 × 91? (a) 810 (b) 81000 (c) 8100
  30. 30.Best estimate of 497 + 249? (a) 700 (b) 900 (c) 500
  31. 31.Best estimate of 94 × 18? (a) 180 (b) 18000 (c) 1800
  32. 32.Best estimate of 522 + 222? (a) 900 (b) 500 (c) 700
  33. 33.Best estimate of 767 + 483? (a) 1500 (b) 1100 (c) 1300
  34. 34.Best estimate of 49 × 51? (a) 25000 (b) 2500 (c) 250
  35. 35.Best estimate of 453 + 510? (a) 1000 (b) 1200 (c) 800
  36. 36.Best estimate of 131 + 675? (a) 800 (b) 1000 (c) 600
  37. 37.Best estimate of 57 × 80? (a) 480 (b) 4800 (c) 48000
  38. 38.Best estimate of 692 + 532? (a) 1000 (b) 1200 (c) 1400
  39. 39.Best estimate of 633 + 190? (a) 1000 (b) 600 (c) 800
  40. 40.Best estimate of 669 + 346? (a) 800 (b) 1200 (c) 1000

Answer key

  1. 6300
  2. 1100
  3. 600
  4. 1000
  5. 700
  6. 1600
  7. 7200
  8. 1200
  9. 3200
  10. 4500
  11. 1300
  12. 1100
  13. 5400
  14. 2700
  15. 4000
  16. 1000
  17. 900
  18. 7200
  19. 4200
  20. 6300
  21. 800
  22. 600
  23. 1400
  24. 1000
  25. 2100
  26. 2400
  27. 2700
  28. 500
  29. 8100
  30. 700
  31. 1800
  32. 700
  33. 1300
  34. 2500
  35. 1000
  36. 800
  37. 4800
  38. 1200
  39. 800
  40. 1000

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