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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 721 · 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 301 + 551? (a) 700 (b) 900 (c) 1100
  2. 2.Best estimate of 777 + 225? (a) 1000 (b) 1200 (c) 800
  3. 3.Best estimate of 29 × 91? (a) 2700 (b) 27000 (c) 270
  4. 4.Best estimate of 657 + 465? (a) 1400 (b) 1200 (c) 1000
  5. 5.Best estimate of 42 × 63? (a) 24000 (b) 240 (c) 2400
  6. 6.Best estimate of 24 × 66? (a) 140 (b) 1400 (c) 14000
  7. 7.Best estimate of 16 × 26? (a) 60 (b) 600 (c) 6000
  8. 8.Best estimate of 39 × 98? (a) 400 (b) 40000 (c) 4000
  9. 9.Best estimate of 722 + 268? (a) 1200 (b) 1000 (c) 800
  10. 10.Best estimate of 238 + 761? (a) 1000 (b) 1200 (c) 800
  11. 11.Best estimate of 16 × 60? (a) 120 (b) 12000 (c) 1200
  12. 12.Best estimate of 77 × 29? (a) 240 (b) 2400 (c) 24000
  13. 13.Best estimate of 832 + 544? (a) 1100 (b) 1300 (c) 1500
  14. 14.Best estimate of 86 × 93? (a) 810 (b) 8100 (c) 81000
  15. 15.Best estimate of 96 × 67? (a) 700 (b) 7000 (c) 70000
  16. 16.Best estimate of 34 × 76? (a) 2400 (b) 240 (c) 24000
  17. 17.Best estimate of 23 × 18? (a) 40 (b) 400 (c) 4000
  18. 18.Best estimate of 38 × 47? (a) 2000 (b) 20000 (c) 200
  19. 19.Best estimate of 136 + 763? (a) 1100 (b) 900 (c) 700
  20. 20.Best estimate of 183 + 284? (a) 300 (b) 700 (c) 500
  21. 21.Best estimate of 86 × 76? (a) 720 (b) 72000 (c) 7200
  22. 22.Best estimate of 79 × 41? (a) 32000 (b) 320 (c) 3200
  23. 23.Best estimate of 60 × 56? (a) 3600 (b) 36000 (c) 360
  24. 24.Best estimate of 689 + 639? (a) 1100 (b) 1500 (c) 1300
  25. 25.Best estimate of 417 + 424? (a) 1000 (b) 800 (c) 600
  26. 26.Best estimate of 408 + 184? (a) 600 (b) 400 (c) 800
  27. 27.Best estimate of 664 + 700? (a) 1400 (b) 1200 (c) 1600
  28. 28.Best estimate of 648 + 454? (a) 900 (b) 1100 (c) 1300
  29. 29.Best estimate of 66 × 14? (a) 7000 (b) 700 (c) 70
  30. 30.Best estimate of 72 × 58? (a) 4200 (b) 42000 (c) 420
  31. 31.Best estimate of 36 × 59? (a) 24000 (b) 240 (c) 2400
  32. 32.Best estimate of 562 + 294? (a) 900 (b) 700 (c) 1100
  33. 33.Best estimate of 16 × 57? (a) 12000 (b) 1200 (c) 120
  34. 34.Best estimate of 61 × 89? (a) 5400 (b) 540 (c) 54000
  35. 35.Best estimate of 23 × 60? (a) 1200 (b) 12000 (c) 120
  36. 36.Best estimate of 13 × 12? (a) 1000 (b) 100 (c) 10
  37. 37.Best estimate of 91 × 86? (a) 81000 (b) 8100 (c) 810
  38. 38.Best estimate of 638 + 203? (a) 800 (b) 600 (c) 1000
  39. 39.Best estimate of 525 + 514? (a) 1200 (b) 800 (c) 1000
  40. 40.Best estimate of 688 + 315? (a) 1000 (b) 1200 (c) 800

Answer key

  1. 900
  2. 1000
  3. 2700
  4. 1200
  5. 2400
  6. 1400
  7. 600
  8. 4000
  9. 1000
  10. 1000
  11. 1200
  12. 2400
  13. 1300
  14. 8100
  15. 7000
  16. 2400
  17. 400
  18. 2000
  19. 900
  20. 500
  21. 7200
  22. 3200
  23. 3600
  24. 1300
  25. 800
  26. 600
  27. 1400
  28. 1100
  29. 700
  30. 4200
  31. 2400
  32. 900
  33. 1200
  34. 5400
  35. 1200
  36. 100
  37. 8100
  38. 800
  39. 1000
  40. 1000

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