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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 170 · 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 792 + 647? (a) 1200 (b) 1600 (c) 1400
  2. 2.Best estimate of 188 + 417? (a) 600 (b) 800 (c) 400
  3. 3.Best estimate of 92 × 84? (a) 7200 (b) 720 (c) 72000
  4. 4.Best estimate of 92 × 26? (a) 270 (b) 27000 (c) 2700
  5. 5.Best estimate of 76 × 56? (a) 48000 (b) 480 (c) 4800
  6. 6.Best estimate of 12 × 32? (a) 3000 (b) 30 (c) 300
  7. 7.Best estimate of 70 × 81? (a) 5600 (b) 56000 (c) 560
  8. 8.Best estimate of 642 + 641? (a) 1000 (b) 1200 (c) 1400
  9. 9.Best estimate of 66 × 84? (a) 560 (b) 5600 (c) 56000
  10. 10.Best estimate of 72 × 29? (a) 2100 (b) 21000 (c) 210
  11. 11.Best estimate of 58 × 39? (a) 24000 (b) 2400 (c) 240
  12. 12.Best estimate of 540 + 845? (a) 1500 (b) 1300 (c) 1100
  13. 13.Best estimate of 325 + 375? (a) 500 (b) 700 (c) 900
  14. 14.Best estimate of 648 + 682? (a) 1300 (b) 1500 (c) 1100
  15. 15.Best estimate of 599 + 839? (a) 1400 (b) 1200 (c) 1600
  16. 16.Best estimate of 88 × 16? (a) 180 (b) 1800 (c) 18000
  17. 17.Best estimate of 148 + 512? (a) 600 (b) 400 (c) 800
  18. 18.Best estimate of 57 × 57? (a) 360 (b) 36000 (c) 3600
  19. 19.Best estimate of 94 × 31? (a) 2700 (b) 27000 (c) 270
  20. 20.Best estimate of 152 + 452? (a) 500 (b) 700 (c) 900
  21. 21.Best estimate of 96 × 14? (a) 1000 (b) 100 (c) 10000
  22. 22.Best estimate of 26 × 24? (a) 60 (b) 600 (c) 6000
  23. 23.Best estimate of 13 × 33? (a) 30 (b) 300 (c) 3000
  24. 24.Best estimate of 76 × 51? (a) 4000 (b) 400 (c) 40000
  25. 25.Best estimate of 123 + 737? (a) 800 (b) 600 (c) 1000
  26. 26.Best estimate of 599 + 462? (a) 1300 (b) 900 (c) 1100
  27. 27.Best estimate of 499 + 457? (a) 1000 (b) 800 (c) 1200
  28. 28.Best estimate of 803 + 252? (a) 900 (b) 1100 (c) 1300
  29. 29.Best estimate of 28 × 23? (a) 600 (b) 6000 (c) 60
  30. 30.Best estimate of 56 × 44? (a) 2400 (b) 24000 (c) 240
  31. 31.Best estimate of 41 × 61? (a) 24000 (b) 2400 (c) 240
  32. 32.Best estimate of 836 + 276? (a) 1100 (b) 1300 (c) 900
  33. 33.Best estimate of 208 + 200? (a) 600 (b) 400 (c) 200
  34. 34.Best estimate of 421 + 436? (a) 800 (b) 1000 (c) 600
  35. 35.Best estimate of 402 + 659? (a) 900 (b) 1100 (c) 1300
  36. 36.Best estimate of 91 × 51? (a) 45000 (b) 4500 (c) 450
  37. 37.Best estimate of 16 × 53? (a) 100 (b) 10000 (c) 1000
  38. 38.Best estimate of 36 × 40? (a) 1600 (b) 16000 (c) 160
  39. 39.Best estimate of 624 + 301? (a) 700 (b) 1100 (c) 900
  40. 40.Best estimate of 78 × 63? (a) 48000 (b) 480 (c) 4800

Answer key

  1. 1400
  2. 600
  3. 7200
  4. 2700
  5. 4800
  6. 300
  7. 5600
  8. 1200
  9. 5600
  10. 2100
  11. 2400
  12. 1300
  13. 700
  14. 1300
  15. 1400
  16. 1800
  17. 600
  18. 3600
  19. 2700
  20. 700
  21. 1000
  22. 600
  23. 300
  24. 4000
  25. 800
  26. 1100
  27. 1000
  28. 1100
  29. 600
  30. 2400
  31. 2400
  32. 1100
  33. 400
  34. 800
  35. 1100
  36. 4500
  37. 1000
  38. 1600
  39. 900
  40. 4800

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