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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 954 · 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 58 × 86? (a) 54000 (b) 5400 (c) 540
  2. 2.Best estimate of 824 + 325? (a) 900 (b) 1100 (c) 1300
  3. 3.Best estimate of 23 × 60? (a) 1200 (b) 12000 (c) 120
  4. 4.Best estimate of 23 × 52? (a) 1000 (b) 100 (c) 10000
  5. 5.Best estimate of 751 + 327? (a) 1300 (b) 1100 (c) 900
  6. 6.Best estimate of 582 + 876? (a) 1500 (b) 1300 (c) 1700
  7. 7.Best estimate of 345 + 492? (a) 1000 (b) 800 (c) 600
  8. 8.Best estimate of 20 × 76? (a) 1600 (b) 160 (c) 16000
  9. 9.Best estimate of 171 + 866? (a) 1300 (b) 1100 (c) 900
  10. 10.Best estimate of 207 + 402? (a) 400 (b) 800 (c) 600
  11. 11.Best estimate of 566 + 519? (a) 1100 (b) 1300 (c) 900
  12. 12.Best estimate of 92 × 91? (a) 8100 (b) 81000 (c) 810
  13. 13.Best estimate of 145 + 778? (a) 900 (b) 1100 (c) 700
  14. 14.Best estimate of 54 × 40? (a) 2000 (b) 20000 (c) 200
  15. 15.Best estimate of 59 × 84? (a) 480 (b) 4800 (c) 48000
  16. 16.Best estimate of 73 × 78? (a) 56000 (b) 560 (c) 5600
  17. 17.Best estimate of 132 + 331? (a) 400 (b) 600 (c) 200
  18. 18.Best estimate of 429 + 769? (a) 1400 (b) 1000 (c) 1200
  19. 19.Best estimate of 716 + 289? (a) 800 (b) 1200 (c) 1000
  20. 20.Best estimate of 61 × 13? (a) 60 (b) 600 (c) 6000
  21. 21.Best estimate of 13 × 12? (a) 1000 (b) 100 (c) 10
  22. 22.Best estimate of 12 × 50? (a) 500 (b) 50 (c) 5000
  23. 23.Best estimate of 30 × 21? (a) 6000 (b) 600 (c) 60
  24. 24.Best estimate of 153 + 159? (a) 400 (b) 600 (c) 200
  25. 25.Best estimate of 83 × 86? (a) 720 (b) 7200 (c) 72000
  26. 26.Best estimate of 553 + 610? (a) 1400 (b) 1200 (c) 1000
  27. 27.Best estimate of 37 × 13? (a) 400 (b) 4000 (c) 40
  28. 28.Best estimate of 98 × 78? (a) 800 (b) 8000 (c) 80000
  29. 29.Best estimate of 31 × 20? (a) 6000 (b) 600 (c) 60
  30. 30.Best estimate of 33 × 63? (a) 18000 (b) 180 (c) 1800
  31. 31.Best estimate of 514 + 358? (a) 700 (b) 1100 (c) 900
  32. 32.Best estimate of 320 + 483? (a) 600 (b) 800 (c) 1000
  33. 33.Best estimate of 69 × 76? (a) 560 (b) 56000 (c) 5600
  34. 34.Best estimate of 509 + 656? (a) 1200 (b) 1400 (c) 1000
  35. 35.Best estimate of 63 × 66? (a) 42000 (b) 420 (c) 4200
  36. 36.Best estimate of 17 × 68? (a) 14000 (b) 140 (c) 1400
  37. 37.Best estimate of 571 + 676? (a) 1500 (b) 1100 (c) 1300
  38. 38.Best estimate of 76 × 52? (a) 40000 (b) 4000 (c) 400
  39. 39.Best estimate of 94 × 29? (a) 270 (b) 2700 (c) 27000
  40. 40.Best estimate of 334 + 344? (a) 400 (b) 800 (c) 600

Answer key

  1. 5400
  2. 1100
  3. 1200
  4. 1000
  5. 1100
  6. 1500
  7. 800
  8. 1600
  9. 1100
  10. 600
  11. 1100
  12. 8100
  13. 900
  14. 2000
  15. 4800
  16. 5600
  17. 400
  18. 1200
  19. 1000
  20. 600
  21. 100
  22. 500
  23. 600
  24. 400
  25. 7200
  26. 1200
  27. 400
  28. 8000
  29. 600
  30. 1800
  31. 900
  32. 800
  33. 5600
  34. 1200
  35. 4200
  36. 1400
  37. 1300
  38. 4000
  39. 2700
  40. 600

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