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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 856 · 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 795 + 560? (a) 1400 (b) 1600 (c) 1200
  2. 2.Best estimate of 539 + 369? (a) 1100 (b) 700 (c) 900
  3. 3.Best estimate of 173 + 825? (a) 800 (b) 1000 (c) 1200
  4. 4.Best estimate of 43 × 16? (a) 8000 (b) 800 (c) 80
  5. 5.Best estimate of 210 + 601? (a) 800 (b) 600 (c) 1000
  6. 6.Best estimate of 16 × 14? (a) 200 (b) 20 (c) 2000
  7. 7.Best estimate of 167 + 236? (a) 400 (b) 600 (c) 200
  8. 8.Best estimate of 43 × 51? (a) 200 (b) 2000 (c) 20000
  9. 9.Best estimate of 287 + 299? (a) 800 (b) 400 (c) 600
  10. 10.Best estimate of 20 × 69? (a) 1400 (b) 14000 (c) 140
  11. 11.Best estimate of 16 × 86? (a) 18000 (b) 180 (c) 1800
  12. 12.Best estimate of 474 + 372? (a) 900 (b) 1100 (c) 700
  13. 13.Best estimate of 355 + 240? (a) 600 (b) 400 (c) 800
  14. 14.Best estimate of 859 + 427? (a) 1100 (b) 1500 (c) 1300
  15. 15.Best estimate of 68 × 92? (a) 630 (b) 63000 (c) 6300
  16. 16.Best estimate of 40 × 93? (a) 360 (b) 3600 (c) 36000
  17. 17.Best estimate of 94 × 87? (a) 81000 (b) 810 (c) 8100
  18. 18.Best estimate of 325 + 563? (a) 1100 (b) 900 (c) 700
  19. 19.Best estimate of 14 × 74? (a) 70 (b) 700 (c) 7000
  20. 20.Best estimate of 67 × 21? (a) 14000 (b) 140 (c) 1400
  21. 21.Best estimate of 628 + 167? (a) 800 (b) 1000 (c) 600
  22. 22.Best estimate of 296 + 278? (a) 800 (b) 600 (c) 400
  23. 23.Best estimate of 781 + 381? (a) 1400 (b) 1000 (c) 1200
  24. 24.Best estimate of 607 + 224? (a) 600 (b) 1000 (c) 800
  25. 25.Best estimate of 196 + 614? (a) 600 (b) 1000 (c) 800
  26. 26.Best estimate of 58 × 42? (a) 240 (b) 2400 (c) 24000
  27. 27.Best estimate of 34 × 49? (a) 150 (b) 1500 (c) 15000
  28. 28.Best estimate of 753 + 259? (a) 1100 (b) 900 (c) 1300
  29. 29.Best estimate of 799 + 670? (a) 1700 (b) 1500 (c) 1300
  30. 30.Best estimate of 534 + 300? (a) 600 (b) 1000 (c) 800
  31. 31.Best estimate of 681 + 664? (a) 1400 (b) 1600 (c) 1200
  32. 32.Best estimate of 633 + 787? (a) 1400 (b) 1600 (c) 1200
  33. 33.Best estimate of 622 + 331? (a) 1100 (b) 900 (c) 700
  34. 34.Best estimate of 86 × 18? (a) 18000 (b) 180 (c) 1800
  35. 35.Best estimate of 64 × 84? (a) 4800 (b) 480 (c) 48000
  36. 36.Best estimate of 40 × 29? (a) 1200 (b) 12000 (c) 120
  37. 37.Best estimate of 86 × 22? (a) 180 (b) 1800 (c) 18000
  38. 38.Best estimate of 64 × 32? (a) 18000 (b) 1800 (c) 180
  39. 39.Best estimate of 711 + 265? (a) 1000 (b) 800 (c) 1200
  40. 40.Best estimate of 21 × 93? (a) 1800 (b) 180 (c) 18000

Answer key

  1. 1400
  2. 900
  3. 1000
  4. 800
  5. 800
  6. 200
  7. 400
  8. 2000
  9. 600
  10. 1400
  11. 1800
  12. 900
  13. 600
  14. 1300
  15. 6300
  16. 3600
  17. 8100
  18. 900
  19. 700
  20. 1400
  21. 800
  22. 600
  23. 1200
  24. 800
  25. 800
  26. 2400
  27. 1500
  28. 1100
  29. 1500
  30. 800
  31. 1400
  32. 1400
  33. 900
  34. 1800
  35. 4800
  36. 1200
  37. 1800
  38. 1800
  39. 1000
  40. 1800

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