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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 542 · 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 170 + 695? (a) 1100 (b) 900 (c) 700
  2. 2.Best estimate of 366 + 277? (a) 700 (b) 900 (c) 500
  3. 3.Best estimate of 633 + 596? (a) 1200 (b) 1400 (c) 1000
  4. 4.Best estimate of 78 × 77? (a) 640 (b) 64000 (c) 6400
  5. 5.Best estimate of 768 + 734? (a) 1500 (b) 1300 (c) 1700
  6. 6.Best estimate of 63 × 90? (a) 5400 (b) 540 (c) 54000
  7. 7.Best estimate of 64 × 93? (a) 54000 (b) 5400 (c) 540
  8. 8.Best estimate of 83 × 34? (a) 2400 (b) 240 (c) 24000
  9. 9.Best estimate of 577 + 135? (a) 500 (b) 700 (c) 900
  10. 10.Best estimate of 655 + 466? (a) 1000 (b) 1200 (c) 1400
  11. 11.Best estimate of 615 + 781? (a) 1200 (b) 1600 (c) 1400
  12. 12.Best estimate of 68 × 92? (a) 6300 (b) 630 (c) 63000
  13. 13.Best estimate of 53 × 31? (a) 150 (b) 1500 (c) 15000
  14. 14.Best estimate of 333 + 655? (a) 1200 (b) 800 (c) 1000
  15. 15.Best estimate of 486 + 293? (a) 800 (b) 1000 (c) 600
  16. 16.Best estimate of 43 × 54? (a) 200 (b) 2000 (c) 20000
  17. 17.Best estimate of 30 × 13? (a) 3000 (b) 30 (c) 300
  18. 18.Best estimate of 511 + 842? (a) 1500 (b) 1100 (c) 1300
  19. 19.Best estimate of 16 × 89? (a) 180 (b) 1800 (c) 18000
  20. 20.Best estimate of 21 × 26? (a) 600 (b) 60 (c) 6000
  21. 21.Best estimate of 580 + 645? (a) 1200 (b) 1400 (c) 1000
  22. 22.Best estimate of 47 × 19? (a) 100 (b) 1000 (c) 10000
  23. 23.Best estimate of 77 × 26? (a) 24000 (b) 240 (c) 2400
  24. 24.Best estimate of 38 × 16? (a) 8000 (b) 800 (c) 80
  25. 25.Best estimate of 134 + 719? (a) 1000 (b) 800 (c) 600
  26. 26.Best estimate of 469 + 747? (a) 1400 (b) 1000 (c) 1200
  27. 27.Best estimate of 28 × 84? (a) 2400 (b) 24000 (c) 240
  28. 28.Best estimate of 268 + 291? (a) 600 (b) 800 (c) 400
  29. 29.Best estimate of 94 × 71? (a) 6300 (b) 63000 (c) 630
  30. 30.Best estimate of 269 + 516? (a) 600 (b) 800 (c) 1000
  31. 31.Best estimate of 28 × 80? (a) 2400 (b) 24000 (c) 240
  32. 32.Best estimate of 66 × 44? (a) 280 (b) 28000 (c) 2800
  33. 33.Best estimate of 173 + 655? (a) 900 (b) 1100 (c) 700
  34. 34.Best estimate of 36 × 46? (a) 2000 (b) 20000 (c) 200
  35. 35.Best estimate of 78 × 60? (a) 48000 (b) 480 (c) 4800
  36. 36.Best estimate of 24 × 61? (a) 1200 (b) 12000 (c) 120
  37. 37.Best estimate of 326 + 712? (a) 1200 (b) 1000 (c) 800
  38. 38.Best estimate of 24 × 78? (a) 16000 (b) 1600 (c) 160
  39. 39.Best estimate of 252 + 133? (a) 600 (b) 200 (c) 400
  40. 40.Best estimate of 226 + 200? (a) 400 (b) 600 (c) 200

Answer key

  1. 900
  2. 700
  3. 1200
  4. 6400
  5. 1500
  6. 5400
  7. 5400
  8. 2400
  9. 700
  10. 1200
  11. 1400
  12. 6300
  13. 1500
  14. 1000
  15. 800
  16. 2000
  17. 300
  18. 1300
  19. 1800
  20. 600
  21. 1200
  22. 1000
  23. 2400
  24. 800
  25. 800
  26. 1200
  27. 2400
  28. 600
  29. 6300
  30. 800
  31. 2400
  32. 2800
  33. 900
  34. 2000
  35. 4800
  36. 1200
  37. 1000
  38. 1600
  39. 400
  40. 400

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