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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 251 · 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 151 + 395? (a) 600 (b) 400 (c) 800
  2. 2.Best estimate of 92 × 17? (a) 180 (b) 18000 (c) 1800
  3. 3.Best estimate of 358 + 475? (a) 700 (b) 900 (c) 1100
  4. 4.Best estimate of 216 + 808? (a) 800 (b) 1200 (c) 1000
  5. 5.Best estimate of 62 × 46? (a) 30000 (b) 3000 (c) 300
  6. 6.Best estimate of 346 + 501? (a) 1000 (b) 600 (c) 800
  7. 7.Best estimate of 235 + 434? (a) 600 (b) 400 (c) 800
  8. 8.Best estimate of 20 × 86? (a) 180 (b) 18000 (c) 1800
  9. 9.Best estimate of 46 × 93? (a) 4500 (b) 45000 (c) 450
  10. 10.Best estimate of 30 × 31? (a) 9000 (b) 90 (c) 900
  11. 11.Best estimate of 235 + 686? (a) 900 (b) 700 (c) 1100
  12. 12.Best estimate of 93 × 23? (a) 180 (b) 1800 (c) 18000
  13. 13.Best estimate of 86 × 48? (a) 45000 (b) 4500 (c) 450
  14. 14.Best estimate of 86 × 27? (a) 2700 (b) 27000 (c) 270
  15. 15.Best estimate of 43 × 92? (a) 3600 (b) 36000 (c) 360
  16. 16.Best estimate of 743 + 492? (a) 1000 (b) 1200 (c) 1400
  17. 17.Best estimate of 381 + 759? (a) 1200 (b) 1400 (c) 1000
  18. 18.Best estimate of 421 + 289? (a) 700 (b) 900 (c) 500
  19. 19.Best estimate of 94 × 37? (a) 3600 (b) 36000 (c) 360
  20. 20.Best estimate of 54 × 78? (a) 4000 (b) 400 (c) 40000
  21. 21.Best estimate of 700 + 529? (a) 1400 (b) 1000 (c) 1200
  22. 22.Best estimate of 413 + 564? (a) 1000 (b) 800 (c) 1200
  23. 23.Best estimate of 38 × 22? (a) 8000 (b) 800 (c) 80
  24. 24.Best estimate of 554 + 272? (a) 700 (b) 900 (c) 1100
  25. 25.Best estimate of 44 × 94? (a) 360 (b) 36000 (c) 3600
  26. 26.Best estimate of 98 × 50? (a) 50000 (b) 500 (c) 5000
  27. 27.Best estimate of 603 + 657? (a) 1100 (b) 1500 (c) 1300
  28. 28.Best estimate of 26 × 73? (a) 210 (b) 21000 (c) 2100
  29. 29.Best estimate of 56 × 14? (a) 600 (b) 60 (c) 6000
  30. 30.Best estimate of 66 × 42? (a) 280 (b) 2800 (c) 28000
  31. 31.Best estimate of 16 × 52? (a) 10000 (b) 1000 (c) 100
  32. 32.Best estimate of 62 × 66? (a) 4200 (b) 420 (c) 42000
  33. 33.Best estimate of 775 + 616? (a) 1600 (b) 1400 (c) 1200
  34. 34.Best estimate of 480 + 130? (a) 600 (b) 400 (c) 800
  35. 35.Best estimate of 418 + 317? (a) 700 (b) 900 (c) 500
  36. 36.Best estimate of 13 × 39? (a) 4000 (b) 400 (c) 40
  37. 37.Best estimate of 33 × 33? (a) 900 (b) 9000 (c) 90
  38. 38.Best estimate of 72 × 93? (a) 630 (b) 63000 (c) 6300
  39. 39.Best estimate of 66 × 73? (a) 49000 (b) 4900 (c) 490
  40. 40.Best estimate of 19 × 24? (a) 40 (b) 400 (c) 4000

Answer key

  1. 600
  2. 1800
  3. 900
  4. 1000
  5. 3000
  6. 800
  7. 600
  8. 1800
  9. 4500
  10. 900
  11. 900
  12. 1800
  13. 4500
  14. 2700
  15. 3600
  16. 1200
  17. 1200
  18. 700
  19. 3600
  20. 4000
  21. 1200
  22. 1000
  23. 800
  24. 900
  25. 3600
  26. 5000
  27. 1300
  28. 2100
  29. 600
  30. 2800
  31. 1000
  32. 4200
  33. 1400
  34. 600
  35. 700
  36. 400
  37. 900
  38. 6300
  39. 4900
  40. 400

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