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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 218 · 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 825 + 162? (a) 1200 (b) 800 (c) 1000
  2. 2.Best estimate of 87 × 16? (a) 18000 (b) 180 (c) 1800
  3. 3.Best estimate of 210 + 255? (a) 700 (b) 500 (c) 300
  4. 4.Best estimate of 21 × 41? (a) 800 (b) 8000 (c) 80
  5. 5.Best estimate of 50 × 58? (a) 3000 (b) 30000 (c) 300
  6. 6.Best estimate of 49 × 92? (a) 450 (b) 4500 (c) 45000
  7. 7.Best estimate of 93 × 38? (a) 3600 (b) 360 (c) 36000
  8. 8.Best estimate of 12 × 82? (a) 80 (b) 800 (c) 8000
  9. 9.Best estimate of 307 + 465? (a) 800 (b) 600 (c) 1000
  10. 10.Best estimate of 134 + 237? (a) 300 (b) 100 (c) 500
  11. 11.Best estimate of 692 + 826? (a) 1300 (b) 1500 (c) 1700
  12. 12.Best estimate of 403 + 136? (a) 700 (b) 300 (c) 500
  13. 13.Best estimate of 69 × 38? (a) 280 (b) 2800 (c) 28000
  14. 14.Best estimate of 646 + 488? (a) 1100 (b) 900 (c) 1300
  15. 15.Best estimate of 790 + 698? (a) 1500 (b) 1700 (c) 1300
  16. 16.Best estimate of 593 + 567? (a) 1000 (b) 1400 (c) 1200
  17. 17.Best estimate of 29 × 33? (a) 900 (b) 9000 (c) 90
  18. 18.Best estimate of 80 × 42? (a) 32000 (b) 320 (c) 3200
  19. 19.Best estimate of 19 × 21? (a) 40 (b) 400 (c) 4000
  20. 20.Best estimate of 56 × 17? (a) 12000 (b) 120 (c) 1200
  21. 21.Best estimate of 155 + 537? (a) 700 (b) 900 (c) 500
  22. 22.Best estimate of 192 + 188? (a) 400 (b) 200 (c) 600
  23. 23.Best estimate of 50 × 84? (a) 40000 (b) 4000 (c) 400
  24. 24.Best estimate of 61 × 48? (a) 300 (b) 30000 (c) 3000
  25. 25.Best estimate of 42 × 62? (a) 24000 (b) 240 (c) 2400
  26. 26.Best estimate of 14 × 33? (a) 300 (b) 3000 (c) 30
  27. 27.Best estimate of 63 × 56? (a) 36000 (b) 360 (c) 3600
  28. 28.Best estimate of 98 × 56? (a) 6000 (b) 60000 (c) 600
  29. 29.Best estimate of 78 × 93? (a) 72000 (b) 720 (c) 7200
  30. 30.Best estimate of 87 × 36? (a) 36000 (b) 360 (c) 3600
  31. 31.Best estimate of 86 × 29? (a) 27000 (b) 2700 (c) 270
  32. 32.Best estimate of 17 × 38? (a) 8000 (b) 800 (c) 80
  33. 33.Best estimate of 33 × 14? (a) 30 (b) 3000 (c) 300
  34. 34.Best estimate of 608 + 480? (a) 900 (b) 1300 (c) 1100
  35. 35.Best estimate of 56 × 79? (a) 48000 (b) 480 (c) 4800
  36. 36.Best estimate of 74 × 38? (a) 280 (b) 28000 (c) 2800
  37. 37.Best estimate of 48 × 48? (a) 250 (b) 2500 (c) 25000
  38. 38.Best estimate of 614 + 192? (a) 1000 (b) 800 (c) 600
  39. 39.Best estimate of 255 + 595? (a) 1100 (b) 700 (c) 900
  40. 40.Best estimate of 46 × 44? (a) 2000 (b) 20000 (c) 200

Answer key

  1. 1000
  2. 1800
  3. 500
  4. 800
  5. 3000
  6. 4500
  7. 3600
  8. 800
  9. 800
  10. 300
  11. 1500
  12. 500
  13. 2800
  14. 1100
  15. 1500
  16. 1200
  17. 900
  18. 3200
  19. 400
  20. 1200
  21. 700
  22. 400
  23. 4000
  24. 3000
  25. 2400
  26. 300
  27. 3600
  28. 6000
  29. 7200
  30. 3600
  31. 2700
  32. 800
  33. 300
  34. 1100
  35. 4800
  36. 2800
  37. 2500
  38. 800
  39. 900
  40. 2000

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