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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 256 · 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 241 + 227? (a) 400 (b) 200 (c) 600
  2. 2.Best estimate of 360 + 333? (a) 900 (b) 500 (c) 700
  3. 3.Best estimate of 42 × 26? (a) 1200 (b) 120 (c) 12000
  4. 4.Best estimate of 215 + 486? (a) 900 (b) 500 (c) 700
  5. 5.Best estimate of 841 + 332? (a) 1300 (b) 900 (c) 1100
  6. 6.Best estimate of 18 × 86? (a) 18000 (b) 180 (c) 1800
  7. 7.Best estimate of 33 × 17? (a) 60 (b) 6000 (c) 600
  8. 8.Best estimate of 23 × 96? (a) 20000 (b) 2000 (c) 200
  9. 9.Best estimate of 860 + 141? (a) 800 (b) 1200 (c) 1000
  10. 10.Best estimate of 711 + 671? (a) 1400 (b) 1600 (c) 1200
  11. 11.Best estimate of 62 × 18? (a) 1200 (b) 120 (c) 12000
  12. 12.Best estimate of 16 × 42? (a) 800 (b) 80 (c) 8000
  13. 13.Best estimate of 96 × 17? (a) 200 (b) 2000 (c) 20000
  14. 14.Best estimate of 81 × 46? (a) 400 (b) 4000 (c) 40000
  15. 15.Best estimate of 411 + 304? (a) 500 (b) 900 (c) 700
  16. 16.Best estimate of 80 × 26? (a) 2400 (b) 24000 (c) 240
  17. 17.Best estimate of 29 × 16? (a) 6000 (b) 60 (c) 600
  18. 18.Best estimate of 27 × 41? (a) 1200 (b) 12000 (c) 120
  19. 19.Best estimate of 469 + 124? (a) 800 (b) 400 (c) 600
  20. 20.Best estimate of 54 × 26? (a) 1500 (b) 15000 (c) 150
  21. 21.Best estimate of 754 + 544? (a) 1100 (b) 1300 (c) 1500
  22. 22.Best estimate of 12 × 66? (a) 700 (b) 7000 (c) 70
  23. 23.Best estimate of 466 + 870? (a) 1600 (b) 1400 (c) 1200
  24. 24.Best estimate of 145 + 389? (a) 500 (b) 300 (c) 700
  25. 25.Best estimate of 48 × 52? (a) 2500 (b) 25000 (c) 250
  26. 26.Best estimate of 196 + 207? (a) 400 (b) 600 (c) 200
  27. 27.Best estimate of 43 × 20? (a) 800 (b) 8000 (c) 80
  28. 28.Best estimate of 228 + 682? (a) 1100 (b) 700 (c) 900
  29. 29.Best estimate of 80 × 84? (a) 64000 (b) 640 (c) 6400
  30. 30.Best estimate of 49 × 30? (a) 1500 (b) 150 (c) 15000
  31. 31.Best estimate of 330 + 385? (a) 500 (b) 900 (c) 700
  32. 32.Best estimate of 799 + 392? (a) 1000 (b) 1400 (c) 1200
  33. 33.Best estimate of 313 + 814? (a) 1100 (b) 900 (c) 1300
  34. 34.Best estimate of 71 × 17? (a) 1400 (b) 14000 (c) 140
  35. 35.Best estimate of 90 × 16? (a) 1800 (b) 180 (c) 18000
  36. 36.Best estimate of 27 × 33? (a) 90 (b) 900 (c) 9000
  37. 37.Best estimate of 76 × 68? (a) 5600 (b) 560 (c) 56000
  38. 38.Best estimate of 96 × 93? (a) 9000 (b) 900 (c) 90000
  39. 39.Best estimate of 44 × 74? (a) 280 (b) 28000 (c) 2800
  40. 40.Best estimate of 94 × 88? (a) 81000 (b) 8100 (c) 810

Answer key

  1. 400
  2. 700
  3. 1200
  4. 700
  5. 1100
  6. 1800
  7. 600
  8. 2000
  9. 1000
  10. 1400
  11. 1200
  12. 800
  13. 2000
  14. 4000
  15. 700
  16. 2400
  17. 600
  18. 1200
  19. 600
  20. 1500
  21. 1300
  22. 700
  23. 1400
  24. 500
  25. 2500
  26. 400
  27. 800
  28. 900
  29. 6400
  30. 1500
  31. 700
  32. 1200
  33. 1100
  34. 1400
  35. 1800
  36. 900
  37. 5600
  38. 9000
  39. 2800
  40. 8100

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