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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 986 · 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 13 × 16? (a) 2000 (b) 200 (c) 20
  2. 2.Best estimate of 19 × 13? (a) 2000 (b) 200 (c) 20
  3. 3.Best estimate of 790 + 658? (a) 1300 (b) 1500 (c) 1700
  4. 4.Best estimate of 70 × 54? (a) 3500 (b) 350 (c) 35000
  5. 5.Best estimate of 213 + 205? (a) 400 (b) 600 (c) 200
  6. 6.Best estimate of 28 × 96? (a) 3000 (b) 30000 (c) 300
  7. 7.Best estimate of 54 × 17? (a) 10000 (b) 100 (c) 1000
  8. 8.Best estimate of 76 × 21? (a) 1600 (b) 16000 (c) 160
  9. 9.Best estimate of 376 + 242? (a) 400 (b) 600 (c) 800
  10. 10.Best estimate of 24 × 56? (a) 1200 (b) 120 (c) 12000
  11. 11.Best estimate of 233 + 225? (a) 200 (b) 400 (c) 600
  12. 12.Best estimate of 71 × 24? (a) 14000 (b) 140 (c) 1400
  13. 13.Best estimate of 80 × 96? (a) 80000 (b) 8000 (c) 800
  14. 14.Best estimate of 47 × 42? (a) 20000 (b) 200 (c) 2000
  15. 15.Best estimate of 664 + 673? (a) 1600 (b) 1400 (c) 1200
  16. 16.Best estimate of 683 + 144? (a) 800 (b) 600 (c) 1000
  17. 17.Best estimate of 237 + 818? (a) 1200 (b) 800 (c) 1000
  18. 18.Best estimate of 521 + 135? (a) 800 (b) 600 (c) 400
  19. 19.Best estimate of 26 × 17? (a) 600 (b) 6000 (c) 60
  20. 20.Best estimate of 759 + 349? (a) 1100 (b) 1300 (c) 900
  21. 21.Best estimate of 71 × 31? (a) 21000 (b) 210 (c) 2100
  22. 22.Best estimate of 723 + 146? (a) 600 (b) 1000 (c) 800
  23. 23.Best estimate of 209 + 863? (a) 1300 (b) 1100 (c) 900
  24. 24.Best estimate of 93 × 52? (a) 45000 (b) 4500 (c) 450
  25. 25.Best estimate of 77 × 61? (a) 48000 (b) 4800 (c) 480
  26. 26.Best estimate of 633 + 325? (a) 900 (b) 700 (c) 1100
  27. 27.Best estimate of 163 + 751? (a) 1000 (b) 800 (c) 1200
  28. 28.Best estimate of 805 + 868? (a) 1500 (b) 1700 (c) 1900
  29. 29.Best estimate of 834 + 266? (a) 1300 (b) 900 (c) 1100
  30. 30.Best estimate of 56 × 36? (a) 24000 (b) 240 (c) 2400
  31. 31.Best estimate of 277 + 170? (a) 500 (b) 700 (c) 300
  32. 32.Best estimate of 267 + 796? (a) 1300 (b) 900 (c) 1100
  33. 33.Best estimate of 274 + 148? (a) 200 (b) 600 (c) 400
  34. 34.Best estimate of 12 × 92? (a) 900 (b) 9000 (c) 90
  35. 35.Best estimate of 66 × 40? (a) 28000 (b) 280 (c) 2800
  36. 36.Best estimate of 201 + 812? (a) 1000 (b) 800 (c) 1200
  37. 37.Best estimate of 27 × 41? (a) 1200 (b) 12000 (c) 120
  38. 38.Best estimate of 82 × 37? (a) 3200 (b) 32000 (c) 320
  39. 39.Best estimate of 78 × 36? (a) 3200 (b) 320 (c) 32000
  40. 40.Best estimate of 13 × 36? (a) 400 (b) 4000 (c) 40

Answer key

  1. 200
  2. 200
  3. 1500
  4. 3500
  5. 400
  6. 3000
  7. 1000
  8. 1600
  9. 600
  10. 1200
  11. 400
  12. 1400
  13. 8000
  14. 2000
  15. 1400
  16. 800
  17. 1000
  18. 600
  19. 600
  20. 1100
  21. 2100
  22. 800
  23. 1100
  24. 4500
  25. 4800
  26. 900
  27. 1000
  28. 1700
  29. 1100
  30. 2400
  31. 500
  32. 1100
  33. 400
  34. 900
  35. 2800
  36. 1000
  37. 1200
  38. 3200
  39. 3200
  40. 400

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