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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 727 · 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 37 × 12? (a) 4000 (b) 40 (c) 400
  2. 2.Best estimate of 26 × 52? (a) 1500 (b) 150 (c) 15000
  3. 3.Best estimate of 19 × 12? (a) 200 (b) 2000 (c) 20
  4. 4.Best estimate of 195 + 480? (a) 900 (b) 700 (c) 500
  5. 5.Best estimate of 558 + 206? (a) 800 (b) 1000 (c) 600
  6. 6.Best estimate of 36 × 22? (a) 800 (b) 80 (c) 8000
  7. 7.Best estimate of 74 × 77? (a) 5600 (b) 56000 (c) 560
  8. 8.Best estimate of 230 + 139? (a) 500 (b) 100 (c) 300
  9. 9.Best estimate of 880 + 484? (a) 1200 (b) 1400 (c) 1600
  10. 10.Best estimate of 462 + 323? (a) 600 (b) 800 (c) 1000
  11. 11.Best estimate of 294 + 585? (a) 900 (b) 700 (c) 1100
  12. 12.Best estimate of 495 + 723? (a) 1000 (b) 1400 (c) 1200
  13. 13.Best estimate of 685 + 725? (a) 1400 (b) 1200 (c) 1600
  14. 14.Best estimate of 307 + 474? (a) 1000 (b) 800 (c) 600
  15. 15.Best estimate of 98 × 74? (a) 700 (b) 7000 (c) 70000
  16. 16.Best estimate of 614 + 445? (a) 800 (b) 1200 (c) 1000
  17. 17.Best estimate of 549 + 739? (a) 1000 (b) 1400 (c) 1200
  18. 18.Best estimate of 310 + 596? (a) 900 (b) 700 (c) 1100
  19. 19.Best estimate of 70 × 77? (a) 5600 (b) 56000 (c) 560
  20. 20.Best estimate of 34 × 57? (a) 18000 (b) 180 (c) 1800
  21. 21.Best estimate of 239 + 332? (a) 700 (b) 500 (c) 300
  22. 22.Best estimate of 130 + 670? (a) 800 (b) 600 (c) 1000
  23. 23.Best estimate of 29 × 58? (a) 180 (b) 1800 (c) 18000
  24. 24.Best estimate of 26 × 26? (a) 900 (b) 9000 (c) 90
  25. 25.Best estimate of 42 × 56? (a) 240 (b) 24000 (c) 2400
  26. 26.Best estimate of 18 × 23? (a) 4000 (b) 400 (c) 40
  27. 27.Best estimate of 98 × 66? (a) 7000 (b) 70000 (c) 700
  28. 28.Best estimate of 52 × 52? (a) 25000 (b) 250 (c) 2500
  29. 29.Best estimate of 424 + 632? (a) 1000 (b) 800 (c) 1200
  30. 30.Best estimate of 40 × 71? (a) 28000 (b) 2800 (c) 280
  31. 31.Best estimate of 209 + 286? (a) 700 (b) 300 (c) 500
  32. 32.Best estimate of 664 + 551? (a) 1500 (b) 1300 (c) 1100
  33. 33.Best estimate of 262 + 479? (a) 800 (b) 1000 (c) 600
  34. 34.Best estimate of 83 × 29? (a) 2400 (b) 24000 (c) 240
  35. 35.Best estimate of 72 × 61? (a) 4200 (b) 42000 (c) 420
  36. 36.Best estimate of 348 + 127? (a) 400 (b) 200 (c) 600
  37. 37.Best estimate of 71 × 33? (a) 21000 (b) 2100 (c) 210
  38. 38.Best estimate of 310 + 132? (a) 400 (b) 600 (c) 200
  39. 39.Best estimate of 43 × 62? (a) 24000 (b) 240 (c) 2400
  40. 40.Best estimate of 57 × 30? (a) 18000 (b) 1800 (c) 180

Answer key

  1. 400
  2. 1500
  3. 200
  4. 700
  5. 800
  6. 800
  7. 5600
  8. 300
  9. 1400
  10. 800
  11. 900
  12. 1200
  13. 1400
  14. 800
  15. 7000
  16. 1000
  17. 1200
  18. 900
  19. 5600
  20. 1800
  21. 500
  22. 800
  23. 1800
  24. 900
  25. 2400
  26. 400
  27. 7000
  28. 2500
  29. 1000
  30. 2800
  31. 500
  32. 1300
  33. 800
  34. 2400
  35. 4200
  36. 400
  37. 2100
  38. 400
  39. 2400
  40. 1800

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