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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 258 · 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 766 + 223? (a) 800 (b) 1200 (c) 1000
  2. 2.Best estimate of 304 + 295? (a) 600 (b) 400 (c) 800
  3. 3.Best estimate of 874 + 827? (a) 1700 (b) 1900 (c) 1500
  4. 4.Best estimate of 464 + 491? (a) 1000 (b) 800 (c) 1200
  5. 5.Best estimate of 270 + 351? (a) 500 (b) 700 (c) 900
  6. 6.Best estimate of 131 + 542? (a) 600 (b) 400 (c) 800
  7. 7.Best estimate of 335 + 671? (a) 1200 (b) 1000 (c) 800
  8. 8.Best estimate of 134 + 388? (a) 500 (b) 300 (c) 700
  9. 9.Best estimate of 74 × 56? (a) 4200 (b) 420 (c) 42000
  10. 10.Best estimate of 420 + 236? (a) 400 (b) 600 (c) 800
  11. 11.Best estimate of 481 + 506? (a) 1000 (b) 1200 (c) 800
  12. 12.Best estimate of 17 × 20? (a) 4000 (b) 400 (c) 40
  13. 13.Best estimate of 179 + 548? (a) 700 (b) 900 (c) 500
  14. 14.Best estimate of 36 × 37? (a) 1600 (b) 16000 (c) 160
  15. 15.Best estimate of 36 × 56? (a) 24000 (b) 240 (c) 2400
  16. 16.Best estimate of 406 + 184? (a) 600 (b) 800 (c) 400
  17. 17.Best estimate of 36 × 38? (a) 160 (b) 16000 (c) 1600
  18. 18.Best estimate of 878 + 138? (a) 800 (b) 1000 (c) 1200
  19. 19.Best estimate of 23 × 27? (a) 600 (b) 6000 (c) 60
  20. 20.Best estimate of 17 × 26? (a) 6000 (b) 60 (c) 600
  21. 21.Best estimate of 754 + 407? (a) 1200 (b) 1400 (c) 1000
  22. 22.Best estimate of 33 × 24? (a) 6000 (b) 60 (c) 600
  23. 23.Best estimate of 44 × 40? (a) 16000 (b) 160 (c) 1600
  24. 24.Best estimate of 47 × 97? (a) 5000 (b) 500 (c) 50000
  25. 25.Best estimate of 84 × 39? (a) 32000 (b) 3200 (c) 320
  26. 26.Best estimate of 18 × 87? (a) 180 (b) 1800 (c) 18000
  27. 27.Best estimate of 32 × 78? (a) 240 (b) 24000 (c) 2400
  28. 28.Best estimate of 57 × 82? (a) 4800 (b) 48000 (c) 480
  29. 29.Best estimate of 66 × 36? (a) 28000 (b) 2800 (c) 280
  30. 30.Best estimate of 765 + 670? (a) 1700 (b) 1500 (c) 1300
  31. 31.Best estimate of 24 × 53? (a) 1000 (b) 10000 (c) 100
  32. 32.Best estimate of 396 + 434? (a) 1000 (b) 600 (c) 800
  33. 33.Best estimate of 31 × 69? (a) 2100 (b) 21000 (c) 210
  34. 34.Best estimate of 530 + 476? (a) 800 (b) 1000 (c) 1200
  35. 35.Best estimate of 649 + 164? (a) 600 (b) 800 (c) 1000
  36. 36.Best estimate of 56 × 69? (a) 42000 (b) 420 (c) 4200
  37. 37.Best estimate of 390 + 520? (a) 700 (b) 900 (c) 1100
  38. 38.Best estimate of 251 + 573? (a) 1100 (b) 900 (c) 700
  39. 39.Best estimate of 200 + 765? (a) 1000 (b) 800 (c) 1200
  40. 40.Best estimate of 76 × 56? (a) 48000 (b) 480 (c) 4800

Answer key

  1. 1000
  2. 600
  3. 1700
  4. 1000
  5. 700
  6. 600
  7. 1000
  8. 500
  9. 4200
  10. 600
  11. 1000
  12. 400
  13. 700
  14. 1600
  15. 2400
  16. 600
  17. 1600
  18. 1000
  19. 600
  20. 600
  21. 1200
  22. 600
  23. 1600
  24. 5000
  25. 3200
  26. 1800
  27. 2400
  28. 4800
  29. 2800
  30. 1500
  31. 1000
  32. 800
  33. 2100
  34. 1000
  35. 800
  36. 4200
  37. 900
  38. 900
  39. 1000
  40. 4800

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