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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 806 · 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 23 × 18? (a) 400 (b) 4000 (c) 40
  2. 2.Best estimate of 51 × 77? (a) 400 (b) 40000 (c) 4000
  3. 3.Best estimate of 856 + 740? (a) 1800 (b) 1600 (c) 1400
  4. 4.Best estimate of 831 + 128? (a) 1100 (b) 900 (c) 700
  5. 5.Best estimate of 291 + 652? (a) 1200 (b) 800 (c) 1000
  6. 6.Best estimate of 68 × 37? (a) 280 (b) 2800 (c) 28000
  7. 7.Best estimate of 712 + 326? (a) 1000 (b) 800 (c) 1200
  8. 8.Best estimate of 97 × 92? (a) 90000 (b) 9000 (c) 900
  9. 9.Best estimate of 720 + 730? (a) 1200 (b) 1600 (c) 1400
  10. 10.Best estimate of 636 + 271? (a) 900 (b) 1100 (c) 700
  11. 11.Best estimate of 13 × 63? (a) 600 (b) 6000 (c) 60
  12. 12.Best estimate of 684 + 398? (a) 900 (b) 1100 (c) 1300
  13. 13.Best estimate of 251 + 457? (a) 1000 (b) 600 (c) 800
  14. 14.Best estimate of 51 × 21? (a) 10000 (b) 1000 (c) 100
  15. 15.Best estimate of 445 + 709? (a) 1300 (b) 1100 (c) 900
  16. 16.Best estimate of 63 × 49? (a) 3000 (b) 30000 (c) 300
  17. 17.Best estimate of 37 × 86? (a) 360 (b) 36000 (c) 3600
  18. 18.Best estimate of 76 × 90? (a) 72000 (b) 7200 (c) 720
  19. 19.Best estimate of 669 + 472? (a) 1200 (b) 1400 (c) 1000
  20. 20.Best estimate of 288 + 331? (a) 600 (b) 800 (c) 400
  21. 21.Best estimate of 682 + 349? (a) 1200 (b) 800 (c) 1000
  22. 22.Best estimate of 310 + 481? (a) 800 (b) 600 (c) 1000
  23. 23.Best estimate of 42 × 94? (a) 3600 (b) 36000 (c) 360
  24. 24.Best estimate of 73 × 86? (a) 63000 (b) 6300 (c) 630
  25. 25.Best estimate of 43 × 96? (a) 400 (b) 40000 (c) 4000
  26. 26.Best estimate of 61 × 96? (a) 600 (b) 6000 (c) 60000
  27. 27.Best estimate of 145 + 473? (a) 800 (b) 600 (c) 400
  28. 28.Best estimate of 49 × 22? (a) 10000 (b) 100 (c) 1000
  29. 29.Best estimate of 26 × 50? (a) 1500 (b) 15000 (c) 150
  30. 30.Best estimate of 413 + 823? (a) 1200 (b) 1000 (c) 1400
  31. 31.Best estimate of 502 + 768? (a) 1300 (b) 1100 (c) 1500
  32. 32.Best estimate of 297 + 424? (a) 900 (b) 500 (c) 700
  33. 33.Best estimate of 14 × 81? (a) 800 (b) 80 (c) 8000
  34. 34.Best estimate of 263 + 325? (a) 800 (b) 400 (c) 600
  35. 35.Best estimate of 31 × 84? (a) 2400 (b) 240 (c) 24000
  36. 36.Best estimate of 209 + 491? (a) 500 (b) 700 (c) 900
  37. 37.Best estimate of 34 × 39? (a) 12000 (b) 120 (c) 1200
  38. 38.Best estimate of 86 × 14? (a) 9000 (b) 900 (c) 90
  39. 39.Best estimate of 14 × 42? (a) 40 (b) 400 (c) 4000
  40. 40.Best estimate of 572 + 598? (a) 1200 (b) 1400 (c) 1000

Answer key

  1. 400
  2. 4000
  3. 1600
  4. 900
  5. 1000
  6. 2800
  7. 1000
  8. 9000
  9. 1400
  10. 900
  11. 600
  12. 1100
  13. 800
  14. 1000
  15. 1100
  16. 3000
  17. 3600
  18. 7200
  19. 1200
  20. 600
  21. 1000
  22. 800
  23. 3600
  24. 6300
  25. 4000
  26. 6000
  27. 600
  28. 1000
  29. 1500
  30. 1200
  31. 1300
  32. 700
  33. 800
  34. 600
  35. 2400
  36. 700
  37. 1200
  38. 900
  39. 400
  40. 1200

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