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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 65 · 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 36 × 54? (a) 200 (b) 20000 (c) 2000
  2. 2.Best estimate of 30 × 71? (a) 21000 (b) 2100 (c) 210
  3. 3.Best estimate of 31 × 92? (a) 270 (b) 27000 (c) 2700
  4. 4.Best estimate of 51 × 64? (a) 30000 (b) 3000 (c) 300
  5. 5.Best estimate of 36 × 89? (a) 360 (b) 36000 (c) 3600
  6. 6.Best estimate of 46 × 29? (a) 15000 (b) 1500 (c) 150
  7. 7.Best estimate of 446 + 320? (a) 900 (b) 500 (c) 700
  8. 8.Best estimate of 71 × 69? (a) 490 (b) 4900 (c) 49000
  9. 9.Best estimate of 24 × 26? (a) 600 (b) 60 (c) 6000
  10. 10.Best estimate of 580 + 530? (a) 900 (b) 1100 (c) 1300
  11. 11.Best estimate of 86 × 57? (a) 540 (b) 5400 (c) 54000
  12. 12.Best estimate of 152 + 169? (a) 400 (b) 600 (c) 200
  13. 13.Best estimate of 73 × 28? (a) 2100 (b) 21000 (c) 210
  14. 14.Best estimate of 571 + 469? (a) 1100 (b) 1300 (c) 900
  15. 15.Best estimate of 799 + 404? (a) 1200 (b) 1000 (c) 1400
  16. 16.Best estimate of 236 + 844? (a) 1000 (b) 800 (c) 1200
  17. 17.Best estimate of 60 × 70? (a) 420 (b) 4200 (c) 42000
  18. 18.Best estimate of 33 × 53? (a) 1500 (b) 150 (c) 15000
  19. 19.Best estimate of 50 × 39? (a) 20000 (b) 2000 (c) 200
  20. 20.Best estimate of 361 + 267? (a) 900 (b) 500 (c) 700
  21. 21.Best estimate of 46 × 86? (a) 450 (b) 4500 (c) 45000
  22. 22.Best estimate of 360 + 618? (a) 1200 (b) 800 (c) 1000
  23. 23.Best estimate of 14 × 53? (a) 500 (b) 5000 (c) 50
  24. 24.Best estimate of 70 × 47? (a) 3500 (b) 35000 (c) 350
  25. 25.Best estimate of 24 × 89? (a) 1800 (b) 180 (c) 18000
  26. 26.Best estimate of 56 × 96? (a) 600 (b) 60000 (c) 6000
  27. 27.Best estimate of 226 + 222? (a) 600 (b) 200 (c) 400
  28. 28.Best estimate of 94 × 78? (a) 72000 (b) 720 (c) 7200
  29. 29.Best estimate of 380 + 851? (a) 1500 (b) 1300 (c) 1100
  30. 30.Best estimate of 52 × 20? (a) 10000 (b) 100 (c) 1000
  31. 31.Best estimate of 258 + 657? (a) 1200 (b) 800 (c) 1000
  32. 32.Best estimate of 786 + 560? (a) 1200 (b) 1600 (c) 1400
  33. 33.Best estimate of 69 × 20? (a) 1400 (b) 14000 (c) 140
  34. 34.Best estimate of 93 × 51? (a) 4500 (b) 45000 (c) 450
  35. 35.Best estimate of 786 + 203? (a) 800 (b) 1000 (c) 1200
  36. 36.Best estimate of 69 × 83? (a) 5600 (b) 560 (c) 56000
  37. 37.Best estimate of 29 × 93? (a) 2700 (b) 27000 (c) 270
  38. 38.Best estimate of 68 × 48? (a) 3500 (b) 350 (c) 35000
  39. 39.Best estimate of 80 × 89? (a) 7200 (b) 720 (c) 72000
  40. 40.Best estimate of 530 + 473? (a) 800 (b) 1000 (c) 1200

Answer key

  1. 2000
  2. 2100
  3. 2700
  4. 3000
  5. 3600
  6. 1500
  7. 700
  8. 4900
  9. 600
  10. 1100
  11. 5400
  12. 400
  13. 2100
  14. 1100
  15. 1200
  16. 1000
  17. 4200
  18. 1500
  19. 2000
  20. 700
  21. 4500
  22. 1000
  23. 500
  24. 3500
  25. 1800
  26. 6000
  27. 400
  28. 7200
  29. 1300
  30. 1000
  31. 1000
  32. 1400
  33. 1400
  34. 4500
  35. 1000
  36. 5600
  37. 2700
  38. 3500
  39. 7200
  40. 1000

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