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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 691 · 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 163 + 617? (a) 600 (b) 1000 (c) 800
  2. 2.Best estimate of 58 × 29? (a) 18000 (b) 180 (c) 1800
  3. 3.Best estimate of 141 + 741? (a) 800 (b) 1000 (c) 600
  4. 4.Best estimate of 203 + 861? (a) 1300 (b) 1100 (c) 900
  5. 5.Best estimate of 775 + 300? (a) 1100 (b) 900 (c) 1300
  6. 6.Best estimate of 31 × 41? (a) 120 (b) 1200 (c) 12000
  7. 7.Best estimate of 21 × 93? (a) 180 (b) 1800 (c) 18000
  8. 8.Best estimate of 221 + 569? (a) 800 (b) 1000 (c) 600
  9. 9.Best estimate of 181 + 766? (a) 1200 (b) 800 (c) 1000
  10. 10.Best estimate of 355 + 598? (a) 1200 (b) 800 (c) 1000
  11. 11.Best estimate of 80 × 24? (a) 160 (b) 1600 (c) 16000
  12. 12.Best estimate of 46 × 30? (a) 15000 (b) 1500 (c) 150
  13. 13.Best estimate of 31 × 92? (a) 2700 (b) 27000 (c) 270
  14. 14.Best estimate of 773 + 329? (a) 1100 (b) 900 (c) 1300
  15. 15.Best estimate of 13 × 13? (a) 100 (b) 1000 (c) 10
  16. 16.Best estimate of 666 + 356? (a) 1300 (b) 1100 (c) 900
  17. 17.Best estimate of 72 × 13? (a) 7000 (b) 70 (c) 700
  18. 18.Best estimate of 56 × 36? (a) 240 (b) 24000 (c) 2400
  19. 19.Best estimate of 46 × 87? (a) 4500 (b) 45000 (c) 450
  20. 20.Best estimate of 226 + 707? (a) 1100 (b) 900 (c) 700
  21. 21.Best estimate of 67 × 72? (a) 490 (b) 49000 (c) 4900
  22. 22.Best estimate of 56 × 16? (a) 1200 (b) 120 (c) 12000
  23. 23.Best estimate of 50 × 50? (a) 25000 (b) 2500 (c) 250
  24. 24.Best estimate of 820 + 170? (a) 1200 (b) 1000 (c) 800
  25. 25.Best estimate of 76 × 59? (a) 48000 (b) 480 (c) 4800
  26. 26.Best estimate of 628 + 590? (a) 1400 (b) 1000 (c) 1200
  27. 27.Best estimate of 445 + 215? (a) 600 (b) 800 (c) 400
  28. 28.Best estimate of 42 × 37? (a) 16000 (b) 1600 (c) 160
  29. 29.Best estimate of 50 × 26? (a) 1500 (b) 150 (c) 15000
  30. 30.Best estimate of 621 + 806? (a) 1200 (b) 1600 (c) 1400
  31. 31.Best estimate of 697 + 310? (a) 1000 (b) 800 (c) 1200
  32. 32.Best estimate of 36 × 31? (a) 120 (b) 1200 (c) 12000
  33. 33.Best estimate of 80 × 66? (a) 560 (b) 5600 (c) 56000
  34. 34.Best estimate of 222 + 204? (a) 400 (b) 200 (c) 600
  35. 35.Best estimate of 16 × 32? (a) 600 (b) 60 (c) 6000
  36. 36.Best estimate of 472 + 759? (a) 1500 (b) 1100 (c) 1300
  37. 37.Best estimate of 169 + 198? (a) 400 (b) 600 (c) 200
  38. 38.Best estimate of 43 × 62? (a) 2400 (b) 240 (c) 24000
  39. 39.Best estimate of 437 + 169? (a) 800 (b) 600 (c) 400
  40. 40.Best estimate of 90 × 66? (a) 63000 (b) 630 (c) 6300

Answer key

  1. 800
  2. 1800
  3. 800
  4. 1100
  5. 1100
  6. 1200
  7. 1800
  8. 800
  9. 1000
  10. 1000
  11. 1600
  12. 1500
  13. 2700
  14. 1100
  15. 100
  16. 1100
  17. 700
  18. 2400
  19. 4500
  20. 900
  21. 4900
  22. 1200
  23. 2500
  24. 1000
  25. 4800
  26. 1200
  27. 600
  28. 1600
  29. 1500
  30. 1400
  31. 1000
  32. 1200
  33. 5600
  34. 400
  35. 600
  36. 1300
  37. 400
  38. 2400
  39. 600
  40. 6300

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