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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 946 · 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 91 × 61? (a) 5400 (b) 540 (c) 54000
  2. 2.Best estimate of 519 + 663? (a) 1400 (b) 1200 (c) 1000
  3. 3.Best estimate of 125 + 353? (a) 300 (b) 500 (c) 700
  4. 4.Best estimate of 668 + 679? (a) 1200 (b) 1400 (c) 1600
  5. 5.Best estimate of 725 + 351? (a) 1100 (b) 900 (c) 1300
  6. 6.Best estimate of 76 × 19? (a) 160 (b) 1600 (c) 16000
  7. 7.Best estimate of 32 × 13? (a) 30 (b) 300 (c) 3000
  8. 8.Best estimate of 728 + 702? (a) 1600 (b) 1200 (c) 1400
  9. 9.Best estimate of 70 × 40? (a) 2800 (b) 28000 (c) 280
  10. 10.Best estimate of 70 × 76? (a) 56000 (b) 560 (c) 5600
  11. 11.Best estimate of 275 + 318? (a) 800 (b) 400 (c) 600
  12. 12.Best estimate of 609 + 792? (a) 1400 (b) 1600 (c) 1200
  13. 13.Best estimate of 730 + 755? (a) 1700 (b) 1500 (c) 1300
  14. 14.Best estimate of 573 + 223? (a) 800 (b) 600 (c) 1000
  15. 15.Best estimate of 28 × 56? (a) 1800 (b) 18000 (c) 180
  16. 16.Best estimate of 649 + 348? (a) 700 (b) 900 (c) 1100
  17. 17.Best estimate of 39 × 57? (a) 240 (b) 2400 (c) 24000
  18. 18.Best estimate of 49 × 23? (a) 100 (b) 10000 (c) 1000
  19. 19.Best estimate of 138 + 553? (a) 700 (b) 500 (c) 900
  20. 20.Best estimate of 192 + 432? (a) 800 (b) 600 (c) 400
  21. 21.Best estimate of 74 × 14? (a) 700 (b) 7000 (c) 70
  22. 22.Best estimate of 766 + 457? (a) 1500 (b) 1300 (c) 1100
  23. 23.Best estimate of 636 + 307? (a) 900 (b) 700 (c) 1100
  24. 24.Best estimate of 559 + 570? (a) 1200 (b) 1000 (c) 1400
  25. 25.Best estimate of 36 × 57? (a) 2400 (b) 240 (c) 24000
  26. 26.Best estimate of 97 × 51? (a) 50000 (b) 500 (c) 5000
  27. 27.Best estimate of 46 × 92? (a) 4500 (b) 45000 (c) 450
  28. 28.Best estimate of 63 × 53? (a) 3000 (b) 30000 (c) 300
  29. 29.Best estimate of 16 × 16? (a) 400 (b) 40 (c) 4000
  30. 30.Best estimate of 798 + 230? (a) 800 (b) 1200 (c) 1000
  31. 31.Best estimate of 204 + 577? (a) 1000 (b) 800 (c) 600
  32. 32.Best estimate of 24 × 28? (a) 600 (b) 6000 (c) 60
  33. 33.Best estimate of 36 × 43? (a) 1600 (b) 160 (c) 16000
  34. 34.Best estimate of 245 + 669? (a) 900 (b) 700 (c) 1100
  35. 35.Best estimate of 73 × 80? (a) 5600 (b) 560 (c) 56000
  36. 36.Best estimate of 741 + 358? (a) 900 (b) 1300 (c) 1100
  37. 37.Best estimate of 360 + 643? (a) 800 (b) 1000 (c) 1200
  38. 38.Best estimate of 381 + 546? (a) 1100 (b) 700 (c) 900
  39. 39.Best estimate of 32 × 36? (a) 120 (b) 12000 (c) 1200
  40. 40.Best estimate of 77 × 38? (a) 3200 (b) 32000 (c) 320

Answer key

  1. 5400
  2. 1200
  3. 500
  4. 1400
  5. 1100
  6. 1600
  7. 300
  8. 1400
  9. 2800
  10. 5600
  11. 600
  12. 1400
  13. 1500
  14. 800
  15. 1800
  16. 900
  17. 2400
  18. 1000
  19. 700
  20. 600
  21. 700
  22. 1300
  23. 900
  24. 1200
  25. 2400
  26. 5000
  27. 4500
  28. 3000
  29. 400
  30. 1000
  31. 800
  32. 600
  33. 1600
  34. 900
  35. 5600
  36. 1100
  37. 1000
  38. 900
  39. 1200
  40. 3200

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