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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 386 · 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 62 × 28? (a) 1800 (b) 18000 (c) 180
  2. 2.Best estimate of 79 × 33? (a) 2400 (b) 240 (c) 24000
  3. 3.Best estimate of 255 + 171? (a) 300 (b) 500 (c) 700
  4. 4.Best estimate of 54 × 32? (a) 150 (b) 15000 (c) 1500
  5. 5.Best estimate of 673 + 488? (a) 1000 (b) 1400 (c) 1200
  6. 6.Best estimate of 26 × 37? (a) 120 (b) 1200 (c) 12000
  7. 7.Best estimate of 500 + 711? (a) 1400 (b) 1000 (c) 1200
  8. 8.Best estimate of 455 + 731? (a) 1200 (b) 1000 (c) 1400
  9. 9.Best estimate of 867 + 176? (a) 900 (b) 1300 (c) 1100
  10. 10.Best estimate of 52 × 83? (a) 4000 (b) 40000 (c) 400
  11. 11.Best estimate of 227 + 551? (a) 1000 (b) 600 (c) 800
  12. 12.Best estimate of 69 × 12? (a) 70 (b) 7000 (c) 700
  13. 13.Best estimate of 407 + 528? (a) 700 (b) 900 (c) 1100
  14. 14.Best estimate of 83 × 74? (a) 560 (b) 5600 (c) 56000
  15. 15.Best estimate of 21 × 12? (a) 200 (b) 2000 (c) 20
  16. 16.Best estimate of 97 × 30? (a) 300 (b) 3000 (c) 30000
  17. 17.Best estimate of 59 × 40? (a) 240 (b) 24000 (c) 2400
  18. 18.Best estimate of 18 × 23? (a) 400 (b) 4000 (c) 40
  19. 19.Best estimate of 68 × 86? (a) 63000 (b) 6300 (c) 630
  20. 20.Best estimate of 78 × 27? (a) 2400 (b) 240 (c) 24000
  21. 21.Best estimate of 67 × 69? (a) 490 (b) 4900 (c) 49000
  22. 22.Best estimate of 88 × 69? (a) 630 (b) 63000 (c) 6300
  23. 23.Best estimate of 842 + 258? (a) 1300 (b) 900 (c) 1100
  24. 24.Best estimate of 149 + 630? (a) 900 (b) 500 (c) 700
  25. 25.Best estimate of 30 × 66? (a) 2100 (b) 210 (c) 21000
  26. 26.Best estimate of 36 × 82? (a) 3200 (b) 32000 (c) 320
  27. 27.Best estimate of 684 + 789? (a) 1700 (b) 1300 (c) 1500
  28. 28.Best estimate of 161 + 764? (a) 1000 (b) 1200 (c) 800
  29. 29.Best estimate of 734 + 536? (a) 1400 (b) 1200 (c) 1000
  30. 30.Best estimate of 13 × 44? (a) 400 (b) 40 (c) 4000
  31. 31.Best estimate of 72 × 78? (a) 5600 (b) 56000 (c) 560
  32. 32.Best estimate of 80 × 61? (a) 480 (b) 48000 (c) 4800
  33. 33.Best estimate of 824 + 192? (a) 1200 (b) 1000 (c) 800
  34. 34.Best estimate of 93 × 96? (a) 9000 (b) 900 (c) 90000
  35. 35.Best estimate of 31 × 16? (a) 600 (b) 6000 (c) 60
  36. 36.Best estimate of 242 + 188? (a) 200 (b) 600 (c) 400
  37. 37.Best estimate of 267 + 434? (a) 700 (b) 500 (c) 900
  38. 38.Best estimate of 332 + 312? (a) 800 (b) 600 (c) 400
  39. 39.Best estimate of 76 × 63? (a) 4800 (b) 480 (c) 48000
  40. 40.Best estimate of 324 + 188? (a) 700 (b) 500 (c) 300

Answer key

  1. 1800
  2. 2400
  3. 500
  4. 1500
  5. 1200
  6. 1200
  7. 1200
  8. 1200
  9. 1100
  10. 4000
  11. 800
  12. 700
  13. 900
  14. 5600
  15. 200
  16. 3000
  17. 2400
  18. 400
  19. 6300
  20. 2400
  21. 4900
  22. 6300
  23. 1100
  24. 700
  25. 2100
  26. 3200
  27. 1500
  28. 1000
  29. 1200
  30. 400
  31. 5600
  32. 4800
  33. 1000
  34. 9000
  35. 600
  36. 400
  37. 700
  38. 600
  39. 4800
  40. 500

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