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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 643 · 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 866 + 614? (a) 1700 (b) 1500 (c) 1300
  2. 2.Best estimate of 319 + 269? (a) 400 (b) 600 (c) 800
  3. 3.Best estimate of 71 × 46? (a) 3500 (b) 350 (c) 35000
  4. 4.Best estimate of 578 + 356? (a) 1000 (b) 800 (c) 1200
  5. 5.Best estimate of 664 + 187? (a) 900 (b) 700 (c) 1100
  6. 6.Best estimate of 16 × 66? (a) 1400 (b) 14000 (c) 140
  7. 7.Best estimate of 305 + 663? (a) 1000 (b) 1200 (c) 800
  8. 8.Best estimate of 239 + 284? (a) 500 (b) 300 (c) 700
  9. 9.Best estimate of 253 + 488? (a) 800 (b) 1000 (c) 600
  10. 10.Best estimate of 340 + 802? (a) 900 (b) 1300 (c) 1100
  11. 11.Best estimate of 66 × 40? (a) 280 (b) 2800 (c) 28000
  12. 12.Best estimate of 18 × 46? (a) 1000 (b) 10000 (c) 100
  13. 13.Best estimate of 640 + 847? (a) 1600 (b) 1400 (c) 1200
  14. 14.Best estimate of 375 + 421? (a) 800 (b) 1000 (c) 600
  15. 15.Best estimate of 204 + 664? (a) 700 (b) 900 (c) 1100
  16. 16.Best estimate of 17 × 64? (a) 12000 (b) 1200 (c) 120
  17. 17.Best estimate of 123 + 151? (a) 100 (b) 500 (c) 300
  18. 18.Best estimate of 37 × 91? (a) 3600 (b) 36000 (c) 360
  19. 19.Best estimate of 657 + 266? (a) 1200 (b) 1000 (c) 800
  20. 20.Best estimate of 510 + 608? (a) 1100 (b) 1300 (c) 900
  21. 21.Best estimate of 647 + 233? (a) 800 (b) 1000 (c) 600
  22. 22.Best estimate of 202 + 259? (a) 700 (b) 500 (c) 300
  23. 23.Best estimate of 90 × 66? (a) 6300 (b) 630 (c) 63000
  24. 24.Best estimate of 26 × 89? (a) 270 (b) 27000 (c) 2700
  25. 25.Best estimate of 694 + 784? (a) 1500 (b) 1300 (c) 1700
  26. 26.Best estimate of 633 + 219? (a) 800 (b) 600 (c) 1000
  27. 27.Best estimate of 16 × 28? (a) 600 (b) 6000 (c) 60
  28. 28.Best estimate of 757 + 700? (a) 1300 (b) 1500 (c) 1700
  29. 29.Best estimate of 19 × 89? (a) 180 (b) 1800 (c) 18000
  30. 30.Best estimate of 19 × 42? (a) 80 (b) 8000 (c) 800
  31. 31.Best estimate of 619 + 137? (a) 500 (b) 700 (c) 900
  32. 32.Best estimate of 272 + 126? (a) 400 (b) 200 (c) 600
  33. 33.Best estimate of 70 × 24? (a) 140 (b) 1400 (c) 14000
  34. 34.Best estimate of 22 × 64? (a) 12000 (b) 120 (c) 1200
  35. 35.Best estimate of 406 + 388? (a) 800 (b) 600 (c) 1000
  36. 36.Best estimate of 83 × 29? (a) 24000 (b) 240 (c) 2400
  37. 37.Best estimate of 16 × 80? (a) 1600 (b) 16000 (c) 160
  38. 38.Best estimate of 24 × 67? (a) 1400 (b) 14000 (c) 140
  39. 39.Best estimate of 251 + 522? (a) 1000 (b) 800 (c) 600
  40. 40.Best estimate of 88 × 69? (a) 630 (b) 63000 (c) 6300

Answer key

  1. 1500
  2. 600
  3. 3500
  4. 1000
  5. 900
  6. 1400
  7. 1000
  8. 500
  9. 800
  10. 1100
  11. 2800
  12. 1000
  13. 1400
  14. 800
  15. 900
  16. 1200
  17. 300
  18. 3600
  19. 1000
  20. 1100
  21. 800
  22. 500
  23. 6300
  24. 2700
  25. 1500
  26. 800
  27. 600
  28. 1500
  29. 1800
  30. 800
  31. 700
  32. 400
  33. 1400
  34. 1200
  35. 800
  36. 2400
  37. 1600
  38. 1400
  39. 800
  40. 6300

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