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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 486 · 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 333 + 158? (a) 500 (b) 700 (c) 300
  2. 2.Best estimate of 33 × 46? (a) 150 (b) 1500 (c) 15000
  3. 3.Best estimate of 827 + 530? (a) 1100 (b) 1300 (c) 1500
  4. 4.Best estimate of 603 + 846? (a) 1600 (b) 1200 (c) 1400
  5. 5.Best estimate of 47 × 13? (a) 5000 (b) 50 (c) 500
  6. 6.Best estimate of 452 + 501? (a) 800 (b) 1000 (c) 1200
  7. 7.Best estimate of 88 × 48? (a) 45000 (b) 4500 (c) 450
  8. 8.Best estimate of 32 × 31? (a) 90 (b) 900 (c) 9000
  9. 9.Best estimate of 36 × 83? (a) 320 (b) 3200 (c) 32000
  10. 10.Best estimate of 47 × 23? (a) 10000 (b) 1000 (c) 100
  11. 11.Best estimate of 97 × 83? (a) 800 (b) 80000 (c) 8000
  12. 12.Best estimate of 596 + 421? (a) 800 (b) 1000 (c) 1200
  13. 13.Best estimate of 96 × 60? (a) 6000 (b) 600 (c) 60000
  14. 14.Best estimate of 12 × 87? (a) 900 (b) 90 (c) 9000
  15. 15.Best estimate of 93 × 26? (a) 2700 (b) 270 (c) 27000
  16. 16.Best estimate of 86 × 89? (a) 81000 (b) 810 (c) 8100
  17. 17.Best estimate of 180 + 851? (a) 1100 (b) 1300 (c) 900
  18. 18.Best estimate of 824 + 690? (a) 1500 (b) 1300 (c) 1700
  19. 19.Best estimate of 68 × 43? (a) 280 (b) 2800 (c) 28000
  20. 20.Best estimate of 174 + 343? (a) 500 (b) 300 (c) 700
  21. 21.Best estimate of 801 + 346? (a) 900 (b) 1100 (c) 1300
  22. 22.Best estimate of 690 + 364? (a) 900 (b) 1300 (c) 1100
  23. 23.Best estimate of 71 × 26? (a) 21000 (b) 2100 (c) 210
  24. 24.Best estimate of 37 × 96? (a) 400 (b) 40000 (c) 4000
  25. 25.Best estimate of 94 × 56? (a) 5400 (b) 540 (c) 54000
  26. 26.Best estimate of 54 × 51? (a) 250 (b) 2500 (c) 25000
  27. 27.Best estimate of 26 × 17? (a) 6000 (b) 600 (c) 60
  28. 28.Best estimate of 33 × 31? (a) 9000 (b) 900 (c) 90
  29. 29.Best estimate of 66 × 90? (a) 6300 (b) 63000 (c) 630
  30. 30.Best estimate of 73 × 26? (a) 2100 (b) 210 (c) 21000
  31. 31.Best estimate of 192 + 167? (a) 400 (b) 200 (c) 600
  32. 32.Best estimate of 467 + 352? (a) 1100 (b) 900 (c) 700
  33. 33.Best estimate of 77 × 22? (a) 16000 (b) 1600 (c) 160
  34. 34.Best estimate of 222 + 264? (a) 500 (b) 700 (c) 300
  35. 35.Best estimate of 12 × 42? (a) 400 (b) 40 (c) 4000
  36. 36.Best estimate of 26 × 76? (a) 24000 (b) 240 (c) 2400
  37. 37.Best estimate of 70 × 18? (a) 1400 (b) 14000 (c) 140
  38. 38.Best estimate of 32 × 77? (a) 2400 (b) 240 (c) 24000
  39. 39.Best estimate of 128 + 484? (a) 400 (b) 800 (c) 600
  40. 40.Best estimate of 32 × 20? (a) 60 (b) 600 (c) 6000

Answer key

  1. 500
  2. 1500
  3. 1300
  4. 1400
  5. 500
  6. 1000
  7. 4500
  8. 900
  9. 3200
  10. 1000
  11. 8000
  12. 1000
  13. 6000
  14. 900
  15. 2700
  16. 8100
  17. 1100
  18. 1500
  19. 2800
  20. 500
  21. 1100
  22. 1100
  23. 2100
  24. 4000
  25. 5400
  26. 2500
  27. 600
  28. 900
  29. 6300
  30. 2100
  31. 400
  32. 900
  33. 1600
  34. 500
  35. 400
  36. 2400
  37. 1400
  38. 2400
  39. 600
  40. 600

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