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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 612 · 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 555 + 323? (a) 700 (b) 900 (c) 1100
  2. 2.Best estimate of 393 + 697? (a) 900 (b) 1100 (c) 1300
  3. 3.Best estimate of 21 × 76? (a) 1600 (b) 16000 (c) 160
  4. 4.Best estimate of 88 × 38? (a) 36000 (b) 3600 (c) 360
  5. 5.Best estimate of 50 × 36? (a) 20000 (b) 2000 (c) 200
  6. 6.Best estimate of 68 × 39? (a) 28000 (b) 280 (c) 2800
  7. 7.Best estimate of 17 × 90? (a) 1800 (b) 180 (c) 18000
  8. 8.Best estimate of 89 × 96? (a) 90000 (b) 900 (c) 9000
  9. 9.Best estimate of 36 × 86? (a) 360 (b) 3600 (c) 36000
  10. 10.Best estimate of 28 × 72? (a) 21000 (b) 2100 (c) 210
  11. 11.Best estimate of 399 + 573? (a) 800 (b) 1200 (c) 1000
  12. 12.Best estimate of 525 + 120? (a) 600 (b) 400 (c) 800
  13. 13.Best estimate of 297 + 120? (a) 600 (b) 200 (c) 400
  14. 14.Best estimate of 27 × 93? (a) 2700 (b) 270 (c) 27000
  15. 15.Best estimate of 46 × 36? (a) 200 (b) 20000 (c) 2000
  16. 16.Best estimate of 77 × 33? (a) 24000 (b) 240 (c) 2400
  17. 17.Best estimate of 16 × 34? (a) 6000 (b) 60 (c) 600
  18. 18.Best estimate of 478 + 554? (a) 1300 (b) 1100 (c) 900
  19. 19.Best estimate of 617 + 308? (a) 1100 (b) 700 (c) 900
  20. 20.Best estimate of 465 + 183? (a) 500 (b) 700 (c) 900
  21. 21.Best estimate of 82 × 46? (a) 40000 (b) 400 (c) 4000
  22. 22.Best estimate of 620 + 300? (a) 1100 (b) 900 (c) 700
  23. 23.Best estimate of 173 + 330? (a) 500 (b) 300 (c) 700
  24. 24.Best estimate of 81 × 68? (a) 56000 (b) 560 (c) 5600
  25. 25.Best estimate of 377 + 758? (a) 1200 (b) 1000 (c) 1400
  26. 26.Best estimate of 74 × 34? (a) 21000 (b) 2100 (c) 210
  27. 27.Best estimate of 424 + 703? (a) 1300 (b) 1100 (c) 900
  28. 28.Best estimate of 436 + 134? (a) 300 (b) 700 (c) 500
  29. 29.Best estimate of 560 + 153? (a) 1000 (b) 800 (c) 600
  30. 30.Best estimate of 30 × 34? (a) 9000 (b) 90 (c) 900
  31. 31.Best estimate of 161 + 213? (a) 200 (b) 600 (c) 400
  32. 32.Best estimate of 22 × 87? (a) 18000 (b) 180 (c) 1800
  33. 33.Best estimate of 28 × 41? (a) 120 (b) 12000 (c) 1200
  34. 34.Best estimate of 56 × 39? (a) 24000 (b) 2400 (c) 240
  35. 35.Best estimate of 276 + 611? (a) 900 (b) 1100 (c) 700
  36. 36.Best estimate of 73 × 76? (a) 560 (b) 56000 (c) 5600
  37. 37.Best estimate of 472 + 139? (a) 600 (b) 400 (c) 800
  38. 38.Best estimate of 567 + 395? (a) 800 (b) 1000 (c) 1200
  39. 39.Best estimate of 603 + 557? (a) 1200 (b) 1400 (c) 1000
  40. 40.Best estimate of 53 × 93? (a) 4500 (b) 450 (c) 45000

Answer key

  1. 900
  2. 1100
  3. 1600
  4. 3600
  5. 2000
  6. 2800
  7. 1800
  8. 9000
  9. 3600
  10. 2100
  11. 1000
  12. 600
  13. 400
  14. 2700
  15. 2000
  16. 2400
  17. 600
  18. 1100
  19. 900
  20. 700
  21. 4000
  22. 900
  23. 500
  24. 5600
  25. 1200
  26. 2100
  27. 1100
  28. 500
  29. 800
  30. 900
  31. 400
  32. 1800
  33. 1200
  34. 2400
  35. 900
  36. 5600
  37. 600
  38. 1000
  39. 1200
  40. 4500

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