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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 371 · 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 40 × 48? (a) 20000 (b) 2000 (c) 200
  2. 2.Best estimate of 765 + 879? (a) 1900 (b) 1500 (c) 1700
  3. 3.Best estimate of 92 × 16? (a) 18000 (b) 180 (c) 1800
  4. 4.Best estimate of 36 × 36? (a) 1600 (b) 16000 (c) 160
  5. 5.Best estimate of 59 × 33? (a) 1800 (b) 180 (c) 18000
  6. 6.Best estimate of 98 × 69? (a) 700 (b) 7000 (c) 70000
  7. 7.Best estimate of 671 + 294? (a) 1000 (b) 1200 (c) 800
  8. 8.Best estimate of 648 + 370? (a) 1000 (b) 1200 (c) 800
  9. 9.Best estimate of 643 + 234? (a) 600 (b) 800 (c) 1000
  10. 10.Best estimate of 773 + 130? (a) 1100 (b) 700 (c) 900
  11. 11.Best estimate of 91 × 19? (a) 180 (b) 18000 (c) 1800
  12. 12.Best estimate of 42 × 76? (a) 32000 (b) 320 (c) 3200
  13. 13.Best estimate of 259 + 183? (a) 500 (b) 300 (c) 700
  14. 14.Best estimate of 21 × 96? (a) 20000 (b) 200 (c) 2000
  15. 15.Best estimate of 176 + 423? (a) 400 (b) 600 (c) 800
  16. 16.Best estimate of 24 × 98? (a) 2000 (b) 20000 (c) 200
  17. 17.Best estimate of 699 + 651? (a) 1600 (b) 1200 (c) 1400
  18. 18.Best estimate of 777 + 667? (a) 1500 (b) 1300 (c) 1700
  19. 19.Best estimate of 440 + 849? (a) 1400 (b) 1200 (c) 1000
  20. 20.Best estimate of 281 + 634? (a) 1100 (b) 900 (c) 700
  21. 21.Best estimate of 751 + 127? (a) 900 (b) 1100 (c) 700
  22. 22.Best estimate of 23 × 97? (a) 20000 (b) 2000 (c) 200
  23. 23.Best estimate of 56 × 42? (a) 2400 (b) 24000 (c) 240
  24. 24.Best estimate of 96 × 86? (a) 90000 (b) 9000 (c) 900
  25. 25.Best estimate of 787 + 465? (a) 1300 (b) 1100 (c) 1500
  26. 26.Best estimate of 742 + 557? (a) 1100 (b) 1500 (c) 1300
  27. 27.Best estimate of 61 × 54? (a) 30000 (b) 3000 (c) 300
  28. 28.Best estimate of 69 × 40? (a) 280 (b) 28000 (c) 2800
  29. 29.Best estimate of 24 × 32? (a) 6000 (b) 600 (c) 60
  30. 30.Best estimate of 54 × 92? (a) 450 (b) 4500 (c) 45000
  31. 31.Best estimate of 360 + 226? (a) 800 (b) 400 (c) 600
  32. 32.Best estimate of 840 + 325? (a) 900 (b) 1300 (c) 1100
  33. 33.Best estimate of 78 × 28? (a) 24000 (b) 2400 (c) 240
  34. 34.Best estimate of 14 × 97? (a) 10000 (b) 1000 (c) 100
  35. 35.Best estimate of 26 × 70? (a) 2100 (b) 21000 (c) 210
  36. 36.Best estimate of 681 + 748? (a) 1600 (b) 1400 (c) 1200
  37. 37.Best estimate of 76 × 98? (a) 80000 (b) 8000 (c) 800
  38. 38.Best estimate of 201 + 614? (a) 1000 (b) 600 (c) 800
  39. 39.Best estimate of 13 × 48? (a) 500 (b) 50 (c) 5000
  40. 40.Best estimate of 391 + 811? (a) 1000 (b) 1200 (c) 1400

Answer key

  1. 2000
  2. 1700
  3. 1800
  4. 1600
  5. 1800
  6. 7000
  7. 1000
  8. 1000
  9. 800
  10. 900
  11. 1800
  12. 3200
  13. 500
  14. 2000
  15. 600
  16. 2000
  17. 1400
  18. 1500
  19. 1200
  20. 900
  21. 900
  22. 2000
  23. 2400
  24. 9000
  25. 1300
  26. 1300
  27. 3000
  28. 2800
  29. 600
  30. 4500
  31. 600
  32. 1100
  33. 2400
  34. 1000
  35. 2100
  36. 1400
  37. 8000
  38. 800
  39. 500
  40. 1200

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