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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 800 · 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 340 + 218? (a) 300 (b) 500 (c) 700
  2. 2.Best estimate of 303 + 691? (a) 800 (b) 1200 (c) 1000
  3. 3.Best estimate of 84 × 56? (a) 4800 (b) 48000 (c) 480
  4. 4.Best estimate of 50 × 48? (a) 250 (b) 2500 (c) 25000
  5. 5.Best estimate of 215 + 587? (a) 1000 (b) 800 (c) 600
  6. 6.Best estimate of 707 + 323? (a) 1000 (b) 1200 (c) 800
  7. 7.Best estimate of 73 × 39? (a) 28000 (b) 280 (c) 2800
  8. 8.Best estimate of 158 + 273? (a) 500 (b) 300 (c) 700
  9. 9.Best estimate of 36 × 71? (a) 28000 (b) 280 (c) 2800
  10. 10.Best estimate of 96 × 87? (a) 900 (b) 90000 (c) 9000
  11. 11.Best estimate of 86 × 78? (a) 7200 (b) 720 (c) 72000
  12. 12.Best estimate of 626 + 302? (a) 1100 (b) 700 (c) 900
  13. 13.Best estimate of 221 + 700? (a) 900 (b) 700 (c) 1100
  14. 14.Best estimate of 622 + 417? (a) 1000 (b) 1200 (c) 800
  15. 15.Best estimate of 57 × 81? (a) 4800 (b) 48000 (c) 480
  16. 16.Best estimate of 79 × 80? (a) 6400 (b) 64000 (c) 640
  17. 17.Best estimate of 378 + 838? (a) 1400 (b) 1200 (c) 1000
  18. 18.Best estimate of 98 × 58? (a) 6000 (b) 60000 (c) 600
  19. 19.Best estimate of 803 + 225? (a) 800 (b) 1200 (c) 1000
  20. 20.Best estimate of 193 + 634? (a) 600 (b) 800 (c) 1000
  21. 21.Best estimate of 305 + 514? (a) 800 (b) 1000 (c) 600
  22. 22.Best estimate of 547 + 371? (a) 1100 (b) 700 (c) 900
  23. 23.Best estimate of 51 × 58? (a) 30000 (b) 3000 (c) 300
  24. 24.Best estimate of 28 × 58? (a) 18000 (b) 1800 (c) 180
  25. 25.Best estimate of 84 × 62? (a) 48000 (b) 4800 (c) 480
  26. 26.Best estimate of 59 × 17? (a) 120 (b) 1200 (c) 12000
  27. 27.Best estimate of 33 × 60? (a) 18000 (b) 1800 (c) 180
  28. 28.Best estimate of 89 × 13? (a) 90 (b) 9000 (c) 900
  29. 29.Best estimate of 14 × 43? (a) 40 (b) 400 (c) 4000
  30. 30.Best estimate of 709 + 161? (a) 700 (b) 900 (c) 1100
  31. 31.Best estimate of 265 + 393? (a) 900 (b) 500 (c) 700
  32. 32.Best estimate of 320 + 407? (a) 700 (b) 500 (c) 900
  33. 33.Best estimate of 544 + 420? (a) 1100 (b) 700 (c) 900
  34. 34.Best estimate of 74 × 56? (a) 4200 (b) 42000 (c) 420
  35. 35.Best estimate of 26 × 23? (a) 600 (b) 6000 (c) 60
  36. 36.Best estimate of 56 × 97? (a) 600 (b) 6000 (c) 60000
  37. 37.Best estimate of 388 + 233? (a) 800 (b) 600 (c) 400
  38. 38.Best estimate of 793 + 211? (a) 800 (b) 1000 (c) 1200
  39. 39.Best estimate of 30 × 24? (a) 60 (b) 600 (c) 6000
  40. 40.Best estimate of 426 + 479? (a) 700 (b) 900 (c) 1100

Answer key

  1. 500
  2. 1000
  3. 4800
  4. 2500
  5. 800
  6. 1000
  7. 2800
  8. 500
  9. 2800
  10. 9000
  11. 7200
  12. 900
  13. 900
  14. 1000
  15. 4800
  16. 6400
  17. 1200
  18. 6000
  19. 1000
  20. 800
  21. 800
  22. 900
  23. 3000
  24. 1800
  25. 4800
  26. 1200
  27. 1800
  28. 900
  29. 400
  30. 900
  31. 700
  32. 700
  33. 900
  34. 4200
  35. 600
  36. 6000
  37. 600
  38. 1000
  39. 600
  40. 900

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