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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 117 · 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 436 + 527? (a) 700 (b) 1100 (c) 900
  2. 2.Best estimate of 90 × 26? (a) 27000 (b) 270 (c) 2700
  3. 3.Best estimate of 134 + 451? (a) 600 (b) 400 (c) 800
  4. 4.Best estimate of 368 + 388? (a) 1000 (b) 600 (c) 800
  5. 5.Best estimate of 19 × 18? (a) 4000 (b) 40 (c) 400
  6. 6.Best estimate of 194 + 793? (a) 1200 (b) 800 (c) 1000
  7. 7.Best estimate of 38 × 78? (a) 32000 (b) 3200 (c) 320
  8. 8.Best estimate of 872 + 657? (a) 1600 (b) 1400 (c) 1800
  9. 9.Best estimate of 56 × 89? (a) 54000 (b) 5400 (c) 540
  10. 10.Best estimate of 144 + 841? (a) 900 (b) 1100 (c) 700
  11. 11.Best estimate of 97 × 14? (a) 100 (b) 1000 (c) 10000
  12. 12.Best estimate of 89 × 49? (a) 4500 (b) 45000 (c) 450
  13. 13.Best estimate of 145 + 469? (a) 400 (b) 800 (c) 600
  14. 14.Best estimate of 40 × 54? (a) 200 (b) 20000 (c) 2000
  15. 15.Best estimate of 40 × 46? (a) 20000 (b) 200 (c) 2000
  16. 16.Best estimate of 843 + 429? (a) 1200 (b) 1400 (c) 1000
  17. 17.Best estimate of 779 + 161? (a) 1000 (b) 800 (c) 1200
  18. 18.Best estimate of 91 × 72? (a) 63000 (b) 630 (c) 6300
  19. 19.Best estimate of 23 × 66? (a) 14000 (b) 1400 (c) 140
  20. 20.Best estimate of 32 × 79? (a) 2400 (b) 240 (c) 24000
  21. 21.Best estimate of 546 + 287? (a) 600 (b) 800 (c) 1000
  22. 22.Best estimate of 87 × 26? (a) 27000 (b) 270 (c) 2700
  23. 23.Best estimate of 472 + 512? (a) 1000 (b) 1200 (c) 800
  24. 24.Best estimate of 527 + 132? (a) 600 (b) 800 (c) 400
  25. 25.Best estimate of 26 × 31? (a) 900 (b) 90 (c) 9000
  26. 26.Best estimate of 88 × 46? (a) 450 (b) 45000 (c) 4500
  27. 27.Best estimate of 47 × 26? (a) 1500 (b) 15000 (c) 150
  28. 28.Best estimate of 81 × 77? (a) 640 (b) 64000 (c) 6400
  29. 29.Best estimate of 495 + 778? (a) 1300 (b) 1100 (c) 1500
  30. 30.Best estimate of 54 × 78? (a) 4000 (b) 40000 (c) 400
  31. 31.Best estimate of 32 × 54? (a) 1500 (b) 150 (c) 15000
  32. 32.Best estimate of 16 × 38? (a) 8000 (b) 80 (c) 800
  33. 33.Best estimate of 176 + 569? (a) 1000 (b) 800 (c) 600
  34. 34.Best estimate of 27 × 44? (a) 1200 (b) 12000 (c) 120
  35. 35.Best estimate of 716 + 741? (a) 1400 (b) 1200 (c) 1600
  36. 36.Best estimate of 67 × 88? (a) 6300 (b) 63000 (c) 630
  37. 37.Best estimate of 572 + 474? (a) 1300 (b) 900 (c) 1100
  38. 38.Best estimate of 32 × 16? (a) 600 (b) 6000 (c) 60
  39. 39.Best estimate of 13 × 53? (a) 5000 (b) 50 (c) 500
  40. 40.Best estimate of 70 × 92? (a) 6300 (b) 63000 (c) 630

Answer key

  1. 900
  2. 2700
  3. 600
  4. 800
  5. 400
  6. 1000
  7. 3200
  8. 1600
  9. 5400
  10. 900
  11. 1000
  12. 4500
  13. 600
  14. 2000
  15. 2000
  16. 1200
  17. 1000
  18. 6300
  19. 1400
  20. 2400
  21. 800
  22. 2700
  23. 1000
  24. 600
  25. 900
  26. 4500
  27. 1500
  28. 6400
  29. 1300
  30. 4000
  31. 1500
  32. 800
  33. 800
  34. 1200
  35. 1400
  36. 6300
  37. 1100
  38. 600
  39. 500
  40. 6300

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