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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 646 · 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 730 + 255? (a) 1000 (b) 800 (c) 1200
  2. 2.Best estimate of 30 × 20? (a) 6000 (b) 60 (c) 600
  3. 3.Best estimate of 533 + 603? (a) 1300 (b) 900 (c) 1100
  4. 4.Best estimate of 126 + 403? (a) 500 (b) 700 (c) 300
  5. 5.Best estimate of 523 + 761? (a) 1500 (b) 1300 (c) 1100
  6. 6.Best estimate of 13 × 51? (a) 5000 (b) 500 (c) 50
  7. 7.Best estimate of 70 × 16? (a) 1400 (b) 140 (c) 14000
  8. 8.Best estimate of 235 + 299? (a) 300 (b) 500 (c) 700
  9. 9.Best estimate of 518 + 423? (a) 900 (b) 1100 (c) 700
  10. 10.Best estimate of 48 × 67? (a) 350 (b) 3500 (c) 35000
  11. 11.Best estimate of 164 + 510? (a) 500 (b) 900 (c) 700
  12. 12.Best estimate of 42 × 42? (a) 160 (b) 1600 (c) 16000
  13. 13.Best estimate of 522 + 746? (a) 1400 (b) 1000 (c) 1200
  14. 14.Best estimate of 606 + 141? (a) 900 (b) 500 (c) 700
  15. 15.Best estimate of 400 + 406? (a) 1000 (b) 800 (c) 600
  16. 16.Best estimate of 323 + 873? (a) 1000 (b) 1400 (c) 1200
  17. 17.Best estimate of 68 × 32? (a) 21000 (b) 210 (c) 2100
  18. 18.Best estimate of 165 + 587? (a) 600 (b) 1000 (c) 800
  19. 19.Best estimate of 26 × 67? (a) 21000 (b) 2100 (c) 210
  20. 20.Best estimate of 94 × 26? (a) 2700 (b) 27000 (c) 270
  21. 21.Best estimate of 289 + 351? (a) 700 (b) 500 (c) 900
  22. 22.Best estimate of 275 + 424? (a) 500 (b) 900 (c) 700
  23. 23.Best estimate of 59 × 81? (a) 480 (b) 48000 (c) 4800
  24. 24.Best estimate of 600 + 184? (a) 1000 (b) 800 (c) 600
  25. 25.Best estimate of 209 + 199? (a) 600 (b) 400 (c) 200
  26. 26.Best estimate of 28 × 80? (a) 240 (b) 2400 (c) 24000
  27. 27.Best estimate of 146 + 878? (a) 800 (b) 1000 (c) 1200
  28. 28.Best estimate of 17 × 36? (a) 80 (b) 8000 (c) 800
  29. 29.Best estimate of 595 + 318? (a) 1100 (b) 700 (c) 900
  30. 30.Best estimate of 422 + 527? (a) 900 (b) 700 (c) 1100
  31. 31.Best estimate of 97 × 60? (a) 60000 (b) 6000 (c) 600
  32. 32.Best estimate of 441 + 482? (a) 900 (b) 700 (c) 1100
  33. 33.Best estimate of 29 × 83? (a) 24000 (b) 2400 (c) 240
  34. 34.Best estimate of 56 × 46? (a) 30000 (b) 300 (c) 3000
  35. 35.Best estimate of 324 + 345? (a) 400 (b) 800 (c) 600
  36. 36.Best estimate of 640 + 864? (a) 1700 (b) 1500 (c) 1300
  37. 37.Best estimate of 667 + 526? (a) 1400 (b) 1000 (c) 1200
  38. 38.Best estimate of 56 × 24? (a) 1200 (b) 120 (c) 12000
  39. 39.Best estimate of 31 × 42? (a) 120 (b) 12000 (c) 1200
  40. 40.Best estimate of 86 × 86? (a) 810 (b) 81000 (c) 8100

Answer key

  1. 1000
  2. 600
  3. 1100
  4. 500
  5. 1300
  6. 500
  7. 1400
  8. 500
  9. 900
  10. 3500
  11. 700
  12. 1600
  13. 1200
  14. 700
  15. 800
  16. 1200
  17. 2100
  18. 800
  19. 2100
  20. 2700
  21. 700
  22. 700
  23. 4800
  24. 800
  25. 400
  26. 2400
  27. 1000
  28. 800
  29. 900
  30. 900
  31. 6000
  32. 900
  33. 2400
  34. 3000
  35. 600
  36. 1500
  37. 1200
  38. 1200
  39. 1200
  40. 8100

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