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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 157 · 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 359 + 410? (a) 600 (b) 1000 (c) 800
  2. 2.Best estimate of 639 + 711? (a) 1100 (b) 1500 (c) 1300
  3. 3.Best estimate of 46 × 78? (a) 4000 (b) 400 (c) 40000
  4. 4.Best estimate of 278 + 620? (a) 700 (b) 1100 (c) 900
  5. 5.Best estimate of 26 × 49? (a) 1500 (b) 150 (c) 15000
  6. 6.Best estimate of 586 + 341? (a) 700 (b) 1100 (c) 900
  7. 7.Best estimate of 38 × 92? (a) 3600 (b) 360 (c) 36000
  8. 8.Best estimate of 578 + 357? (a) 1000 (b) 1200 (c) 800
  9. 9.Best estimate of 90 × 57? (a) 54000 (b) 5400 (c) 540
  10. 10.Best estimate of 83 × 82? (a) 640 (b) 6400 (c) 64000
  11. 11.Best estimate of 299 + 289? (a) 400 (b) 600 (c) 800
  12. 12.Best estimate of 430 + 276? (a) 900 (b) 700 (c) 500
  13. 13.Best estimate of 498 + 585? (a) 1100 (b) 900 (c) 1300
  14. 14.Best estimate of 92 × 84? (a) 72000 (b) 720 (c) 7200
  15. 15.Best estimate of 62 × 47? (a) 3000 (b) 30000 (c) 300
  16. 16.Best estimate of 77 × 66? (a) 56000 (b) 5600 (c) 560
  17. 17.Best estimate of 80 × 70? (a) 560 (b) 56000 (c) 5600
  18. 18.Best estimate of 215 + 521? (a) 700 (b) 900 (c) 500
  19. 19.Best estimate of 26 × 31? (a) 900 (b) 9000 (c) 90
  20. 20.Best estimate of 76 × 32? (a) 240 (b) 2400 (c) 24000
  21. 21.Best estimate of 52 × 71? (a) 3500 (b) 35000 (c) 350
  22. 22.Best estimate of 251 + 873? (a) 1200 (b) 1000 (c) 1400
  23. 23.Best estimate of 715 + 730? (a) 1200 (b) 1400 (c) 1600
  24. 24.Best estimate of 93 × 58? (a) 54000 (b) 540 (c) 5400
  25. 25.Best estimate of 92 × 79? (a) 720 (b) 72000 (c) 7200
  26. 26.Best estimate of 36 × 30? (a) 120 (b) 12000 (c) 1200
  27. 27.Best estimate of 184 + 715? (a) 1100 (b) 900 (c) 700
  28. 28.Best estimate of 643 + 664? (a) 1500 (b) 1300 (c) 1100
  29. 29.Best estimate of 324 + 590? (a) 900 (b) 1100 (c) 700
  30. 30.Best estimate of 439 + 244? (a) 800 (b) 600 (c) 400
  31. 31.Best estimate of 194 + 122? (a) 100 (b) 300 (c) 500
  32. 32.Best estimate of 22 × 56? (a) 1200 (b) 12000 (c) 120
  33. 33.Best estimate of 76 × 50? (a) 400 (b) 40000 (c) 4000
  34. 34.Best estimate of 447 + 441? (a) 800 (b) 600 (c) 1000
  35. 35.Best estimate of 701 + 517? (a) 1200 (b) 1400 (c) 1000
  36. 36.Best estimate of 288 + 541? (a) 600 (b) 800 (c) 1000
  37. 37.Best estimate of 243 + 386? (a) 800 (b) 600 (c) 400
  38. 38.Best estimate of 212 + 231? (a) 200 (b) 400 (c) 600
  39. 39.Best estimate of 239 + 387? (a) 400 (b) 600 (c) 800
  40. 40.Best estimate of 86 × 17? (a) 1800 (b) 18000 (c) 180

Answer key

  1. 800
  2. 1300
  3. 4000
  4. 900
  5. 1500
  6. 900
  7. 3600
  8. 1000
  9. 5400
  10. 6400
  11. 600
  12. 700
  13. 1100
  14. 7200
  15. 3000
  16. 5600
  17. 5600
  18. 700
  19. 900
  20. 2400
  21. 3500
  22. 1200
  23. 1400
  24. 5400
  25. 7200
  26. 1200
  27. 900
  28. 1300
  29. 900
  30. 600
  31. 300
  32. 1200
  33. 4000
  34. 800
  35. 1200
  36. 800
  37. 600
  38. 400
  39. 600
  40. 1800

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