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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 402 · 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 430 + 404? (a) 1000 (b) 600 (c) 800
  2. 2.Best estimate of 651 + 773? (a) 1700 (b) 1500 (c) 1300
  3. 3.Best estimate of 579 + 637? (a) 1400 (b) 1200 (c) 1000
  4. 4.Best estimate of 59 × 54? (a) 3000 (b) 30000 (c) 300
  5. 5.Best estimate of 19 × 74? (a) 140 (b) 14000 (c) 1400
  6. 6.Best estimate of 37 × 49? (a) 2000 (b) 200 (c) 20000
  7. 7.Best estimate of 36 × 93? (a) 36000 (b) 3600 (c) 360
  8. 8.Best estimate of 84 × 63? (a) 480 (b) 48000 (c) 4800
  9. 9.Best estimate of 66 × 50? (a) 35000 (b) 3500 (c) 350
  10. 10.Best estimate of 12 × 72? (a) 700 (b) 70 (c) 7000
  11. 11.Best estimate of 84 × 62? (a) 48000 (b) 480 (c) 4800
  12. 12.Best estimate of 249 + 251? (a) 700 (b) 300 (c) 500
  13. 13.Best estimate of 402 + 148? (a) 700 (b) 500 (c) 300
  14. 14.Best estimate of 87 × 31? (a) 2700 (b) 270 (c) 27000
  15. 15.Best estimate of 31 × 80? (a) 240 (b) 24000 (c) 2400
  16. 16.Best estimate of 606 + 637? (a) 1000 (b) 1200 (c) 1400
  17. 17.Best estimate of 66 × 16? (a) 140 (b) 14000 (c) 1400
  18. 18.Best estimate of 17 × 80? (a) 1600 (b) 16000 (c) 160
  19. 19.Best estimate of 21 × 41? (a) 800 (b) 8000 (c) 80
  20. 20.Best estimate of 253 + 832? (a) 1100 (b) 900 (c) 1300
  21. 21.Best estimate of 305 + 414? (a) 900 (b) 500 (c) 700
  22. 22.Best estimate of 268 + 663? (a) 1000 (b) 1200 (c) 800
  23. 23.Best estimate of 124 + 694? (a) 800 (b) 1000 (c) 600
  24. 24.Best estimate of 461 + 637? (a) 1100 (b) 900 (c) 1300
  25. 25.Best estimate of 196 + 659? (a) 900 (b) 1100 (c) 700
  26. 26.Best estimate of 59 × 13? (a) 600 (b) 60 (c) 6000
  27. 27.Best estimate of 30 × 77? (a) 240 (b) 2400 (c) 24000
  28. 28.Best estimate of 12 × 80? (a) 8000 (b) 800 (c) 80
  29. 29.Best estimate of 59 × 17? (a) 1200 (b) 120 (c) 12000
  30. 30.Best estimate of 244 + 831? (a) 800 (b) 1000 (c) 1200
  31. 31.Best estimate of 139 + 837? (a) 900 (b) 700 (c) 1100
  32. 32.Best estimate of 26 × 14? (a) 300 (b) 3000 (c) 30
  33. 33.Best estimate of 335 + 201? (a) 700 (b) 500 (c) 300
  34. 34.Best estimate of 36 × 96? (a) 4000 (b) 40000 (c) 400
  35. 35.Best estimate of 273 + 269? (a) 600 (b) 400 (c) 800
  36. 36.Best estimate of 186 + 533? (a) 700 (b) 900 (c) 500
  37. 37.Best estimate of 702 + 606? (a) 1100 (b) 1500 (c) 1300
  38. 38.Best estimate of 53 × 29? (a) 15000 (b) 150 (c) 1500
  39. 39.Best estimate of 48 × 26? (a) 150 (b) 1500 (c) 15000
  40. 40.Best estimate of 653 + 258? (a) 1200 (b) 1000 (c) 800

Answer key

  1. 800
  2. 1500
  3. 1200
  4. 3000
  5. 1400
  6. 2000
  7. 3600
  8. 4800
  9. 3500
  10. 700
  11. 4800
  12. 500
  13. 500
  14. 2700
  15. 2400
  16. 1200
  17. 1400
  18. 1600
  19. 800
  20. 1100
  21. 700
  22. 1000
  23. 800
  24. 1100
  25. 900
  26. 600
  27. 2400
  28. 800
  29. 1200
  30. 1000
  31. 900
  32. 300
  33. 500
  34. 4000
  35. 600
  36. 700
  37. 1300
  38. 1500
  39. 1500
  40. 1000

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