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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 732 · 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 743 + 229? (a) 700 (b) 1100 (c) 900
  2. 2.Best estimate of 251 + 830? (a) 1300 (b) 1100 (c) 900
  3. 3.Best estimate of 251 + 792? (a) 1100 (b) 900 (c) 1300
  4. 4.Best estimate of 39 × 61? (a) 2400 (b) 240 (c) 24000
  5. 5.Best estimate of 76 × 49? (a) 40000 (b) 4000 (c) 400
  6. 6.Best estimate of 97 × 73? (a) 7000 (b) 70000 (c) 700
  7. 7.Best estimate of 90 × 56? (a) 54000 (b) 5400 (c) 540
  8. 8.Best estimate of 226 + 312? (a) 300 (b) 700 (c) 500
  9. 9.Best estimate of 77 × 94? (a) 72000 (b) 7200 (c) 720
  10. 10.Best estimate of 283 + 653? (a) 1200 (b) 1000 (c) 800
  11. 11.Best estimate of 557 + 342? (a) 900 (b) 1100 (c) 700
  12. 12.Best estimate of 86 × 42? (a) 360 (b) 36000 (c) 3600
  13. 13.Best estimate of 33 × 54? (a) 150 (b) 15000 (c) 1500
  14. 14.Best estimate of 90 × 13? (a) 9000 (b) 900 (c) 90
  15. 15.Best estimate of 56 × 13? (a) 6000 (b) 600 (c) 60
  16. 16.Best estimate of 87 × 59? (a) 54000 (b) 5400 (c) 540
  17. 17.Best estimate of 604 + 372? (a) 800 (b) 1200 (c) 1000
  18. 18.Best estimate of 222 + 166? (a) 200 (b) 600 (c) 400
  19. 19.Best estimate of 43 × 22? (a) 8000 (b) 800 (c) 80
  20. 20.Best estimate of 12 × 40? (a) 4000 (b) 40 (c) 400
  21. 21.Best estimate of 59 × 56? (a) 360 (b) 3600 (c) 36000
  22. 22.Best estimate of 31 × 30? (a) 9000 (b) 90 (c) 900
  23. 23.Best estimate of 66 × 16? (a) 14000 (b) 140 (c) 1400
  24. 24.Best estimate of 49 × 36? (a) 2000 (b) 20000 (c) 200
  25. 25.Best estimate of 36 × 47? (a) 20000 (b) 200 (c) 2000
  26. 26.Best estimate of 74 × 38? (a) 28000 (b) 2800 (c) 280
  27. 27.Best estimate of 685 + 403? (a) 1300 (b) 1100 (c) 900
  28. 28.Best estimate of 12 × 88? (a) 9000 (b) 900 (c) 90
  29. 29.Best estimate of 613 + 444? (a) 1200 (b) 800 (c) 1000
  30. 30.Best estimate of 70 × 31? (a) 210 (b) 21000 (c) 2100
  31. 31.Best estimate of 787 + 753? (a) 1400 (b) 1800 (c) 1600
  32. 32.Best estimate of 278 + 192? (a) 500 (b) 300 (c) 700
  33. 33.Best estimate of 26 × 26? (a) 90 (b) 9000 (c) 900
  34. 34.Best estimate of 50 × 80? (a) 400 (b) 40000 (c) 4000
  35. 35.Best estimate of 714 + 556? (a) 1500 (b) 1100 (c) 1300
  36. 36.Best estimate of 93 × 76? (a) 72000 (b) 7200 (c) 720
  37. 37.Best estimate of 662 + 794? (a) 1300 (b) 1700 (c) 1500
  38. 38.Best estimate of 94 × 98? (a) 900 (b) 9000 (c) 90000
  39. 39.Best estimate of 141 + 677? (a) 1000 (b) 600 (c) 800
  40. 40.Best estimate of 46 × 93? (a) 4500 (b) 45000 (c) 450

Answer key

  1. 900
  2. 1100
  3. 1100
  4. 2400
  5. 4000
  6. 7000
  7. 5400
  8. 500
  9. 7200
  10. 1000
  11. 900
  12. 3600
  13. 1500
  14. 900
  15. 600
  16. 5400
  17. 1000
  18. 400
  19. 800
  20. 400
  21. 3600
  22. 900
  23. 1400
  24. 2000
  25. 2000
  26. 2800
  27. 1100
  28. 900
  29. 1000
  30. 2100
  31. 1600
  32. 500
  33. 900
  34. 4000
  35. 1300
  36. 7200
  37. 1500
  38. 9000
  39. 800
  40. 4500

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