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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 586 · 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 63 × 21? (a) 1200 (b) 12000 (c) 120
  2. 2.Best estimate of 33 × 31? (a) 90 (b) 9000 (c) 900
  3. 3.Best estimate of 43 × 76? (a) 320 (b) 32000 (c) 3200
  4. 4.Best estimate of 97 × 28? (a) 30000 (b) 300 (c) 3000
  5. 5.Best estimate of 29 × 54? (a) 150 (b) 15000 (c) 1500
  6. 6.Best estimate of 870 + 433? (a) 1300 (b) 1100 (c) 1500
  7. 7.Best estimate of 692 + 459? (a) 1400 (b) 1000 (c) 1200
  8. 8.Best estimate of 411 + 282? (a) 500 (b) 900 (c) 700
  9. 9.Best estimate of 21 × 36? (a) 8000 (b) 80 (c) 800
  10. 10.Best estimate of 71 × 89? (a) 63000 (b) 6300 (c) 630
  11. 11.Best estimate of 161 + 324? (a) 300 (b) 500 (c) 700
  12. 12.Best estimate of 46 × 37? (a) 200 (b) 20000 (c) 2000
  13. 13.Best estimate of 694 + 406? (a) 1300 (b) 900 (c) 1100
  14. 14.Best estimate of 56 × 30? (a) 1800 (b) 18000 (c) 180
  15. 15.Best estimate of 831 + 762? (a) 1800 (b) 1400 (c) 1600
  16. 16.Best estimate of 162 + 854? (a) 1300 (b) 1100 (c) 900
  17. 17.Best estimate of 31 × 56? (a) 180 (b) 18000 (c) 1800
  18. 18.Best estimate of 791 + 293? (a) 1100 (b) 900 (c) 1300
  19. 19.Best estimate of 91 × 84? (a) 720 (b) 7200 (c) 72000
  20. 20.Best estimate of 528 + 541? (a) 800 (b) 1200 (c) 1000
  21. 21.Best estimate of 71 × 86? (a) 6300 (b) 630 (c) 63000
  22. 22.Best estimate of 224 + 572? (a) 1000 (b) 800 (c) 600
  23. 23.Best estimate of 50 × 29? (a) 1500 (b) 15000 (c) 150
  24. 24.Best estimate of 818 + 493? (a) 1100 (b) 1500 (c) 1300
  25. 25.Best estimate of 76 × 54? (a) 400 (b) 4000 (c) 40000
  26. 26.Best estimate of 30 × 89? (a) 270 (b) 2700 (c) 27000
  27. 27.Best estimate of 832 + 809? (a) 1800 (b) 1600 (c) 1400
  28. 28.Best estimate of 60 × 18? (a) 12000 (b) 1200 (c) 120
  29. 29.Best estimate of 36 × 13? (a) 40 (b) 400 (c) 4000
  30. 30.Best estimate of 575 + 281? (a) 1100 (b) 900 (c) 700
  31. 31.Best estimate of 752 + 877? (a) 1700 (b) 1500 (c) 1900
  32. 32.Best estimate of 26 × 66? (a) 21000 (b) 2100 (c) 210
  33. 33.Best estimate of 31 × 42? (a) 1200 (b) 12000 (c) 120
  34. 34.Best estimate of 93 × 52? (a) 4500 (b) 45000 (c) 450
  35. 35.Best estimate of 392 + 762? (a) 1400 (b) 1000 (c) 1200
  36. 36.Best estimate of 526 + 860? (a) 1200 (b) 1600 (c) 1400
  37. 37.Best estimate of 248 + 184? (a) 400 (b) 200 (c) 600
  38. 38.Best estimate of 91 × 46? (a) 4500 (b) 45000 (c) 450
  39. 39.Best estimate of 691 + 840? (a) 1300 (b) 1700 (c) 1500
  40. 40.Best estimate of 258 + 769? (a) 1300 (b) 1100 (c) 900

Answer key

  1. 1200
  2. 900
  3. 3200
  4. 3000
  5. 1500
  6. 1300
  7. 1200
  8. 700
  9. 800
  10. 6300
  11. 500
  12. 2000
  13. 1100
  14. 1800
  15. 1600
  16. 1100
  17. 1800
  18. 1100
  19. 7200
  20. 1000
  21. 6300
  22. 800
  23. 1500
  24. 1300
  25. 4000
  26. 2700
  27. 1600
  28. 1200
  29. 400
  30. 900
  31. 1700
  32. 2100
  33. 1200
  34. 4500
  35. 1200
  36. 1400
  37. 400
  38. 4500
  39. 1500
  40. 1100

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