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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 519 · 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 21 × 33? (a) 600 (b) 60 (c) 6000
  2. 2.Best estimate of 844 + 189? (a) 1000 (b) 800 (c) 1200
  3. 3.Best estimate of 23 × 47? (a) 100 (b) 1000 (c) 10000
  4. 4.Best estimate of 29 × 38? (a) 1200 (b) 12000 (c) 120
  5. 5.Best estimate of 532 + 315? (a) 1000 (b) 800 (c) 600
  6. 6.Best estimate of 810 + 343? (a) 900 (b) 1300 (c) 1100
  7. 7.Best estimate of 87 × 51? (a) 45000 (b) 450 (c) 4500
  8. 8.Best estimate of 625 + 520? (a) 1100 (b) 900 (c) 1300
  9. 9.Best estimate of 74 × 93? (a) 6300 (b) 630 (c) 63000
  10. 10.Best estimate of 195 + 524? (a) 500 (b) 700 (c) 900
  11. 11.Best estimate of 86 × 50? (a) 450 (b) 4500 (c) 45000
  12. 12.Best estimate of 64 × 86? (a) 5400 (b) 54000 (c) 540
  13. 13.Best estimate of 706 + 190? (a) 900 (b) 700 (c) 1100
  14. 14.Best estimate of 59 × 39? (a) 2400 (b) 240 (c) 24000
  15. 15.Best estimate of 380 + 309? (a) 500 (b) 900 (c) 700
  16. 16.Best estimate of 155 + 195? (a) 400 (b) 200 (c) 600
  17. 17.Best estimate of 356 + 720? (a) 1100 (b) 1300 (c) 900
  18. 18.Best estimate of 137 + 434? (a) 500 (b) 700 (c) 300
  19. 19.Best estimate of 23 × 90? (a) 18000 (b) 180 (c) 1800
  20. 20.Best estimate of 470 + 472? (a) 1000 (b) 1200 (c) 800
  21. 21.Best estimate of 51 × 49? (a) 25000 (b) 250 (c) 2500
  22. 22.Best estimate of 58 × 58? (a) 36000 (b) 3600 (c) 360
  23. 23.Best estimate of 89 × 33? (a) 27000 (b) 2700 (c) 270
  24. 24.Best estimate of 265 + 430? (a) 900 (b) 700 (c) 500
  25. 25.Best estimate of 633 + 699? (a) 1300 (b) 1500 (c) 1100
  26. 26.Best estimate of 86 × 67? (a) 630 (b) 63000 (c) 6300
  27. 27.Best estimate of 414 + 331? (a) 500 (b) 700 (c) 900
  28. 28.Best estimate of 626 + 539? (a) 1100 (b) 1300 (c) 900
  29. 29.Best estimate of 63 × 90? (a) 54000 (b) 5400 (c) 540
  30. 30.Best estimate of 49 × 90? (a) 450 (b) 45000 (c) 4500
  31. 31.Best estimate of 720 + 184? (a) 900 (b) 1100 (c) 700
  32. 32.Best estimate of 41 × 86? (a) 3600 (b) 360 (c) 36000
  33. 33.Best estimate of 94 × 50? (a) 450 (b) 45000 (c) 4500
  34. 34.Best estimate of 93 × 88? (a) 8100 (b) 810 (c) 81000
  35. 35.Best estimate of 267 + 345? (a) 800 (b) 400 (c) 600
  36. 36.Best estimate of 756 + 446? (a) 1400 (b) 1000 (c) 1200
  37. 37.Best estimate of 66 × 32? (a) 210 (b) 21000 (c) 2100
  38. 38.Best estimate of 87 × 86? (a) 810 (b) 8100 (c) 81000
  39. 39.Best estimate of 234 + 213? (a) 600 (b) 200 (c) 400
  40. 40.Best estimate of 86 × 94? (a) 81000 (b) 810 (c) 8100

Answer key

  1. 600
  2. 1000
  3. 1000
  4. 1200
  5. 800
  6. 1100
  7. 4500
  8. 1100
  9. 6300
  10. 700
  11. 4500
  12. 5400
  13. 900
  14. 2400
  15. 700
  16. 400
  17. 1100
  18. 500
  19. 1800
  20. 1000
  21. 2500
  22. 3600
  23. 2700
  24. 700
  25. 1300
  26. 6300
  27. 700
  28. 1100
  29. 5400
  30. 4500
  31. 900
  32. 3600
  33. 4500
  34. 8100
  35. 600
  36. 1200
  37. 2100
  38. 8100
  39. 400
  40. 8100

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