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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 763 · 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 494 + 165? (a) 700 (b) 900 (c) 500
  2. 2.Best estimate of 256 + 377? (a) 700 (b) 900 (c) 500
  3. 3.Best estimate of 68 × 21? (a) 140 (b) 1400 (c) 14000
  4. 4.Best estimate of 37 × 20? (a) 8000 (b) 800 (c) 80
  5. 5.Best estimate of 642 + 771? (a) 1200 (b) 1600 (c) 1400
  6. 6.Best estimate of 604 + 136? (a) 500 (b) 700 (c) 900
  7. 7.Best estimate of 22 × 64? (a) 120 (b) 12000 (c) 1200
  8. 8.Best estimate of 419 + 878? (a) 1100 (b) 1500 (c) 1300
  9. 9.Best estimate of 74 × 94? (a) 63000 (b) 6300 (c) 630
  10. 10.Best estimate of 664 + 202? (a) 1100 (b) 700 (c) 900
  11. 11.Best estimate of 812 + 856? (a) 1900 (b) 1700 (c) 1500
  12. 12.Best estimate of 465 + 597? (a) 1100 (b) 900 (c) 1300
  13. 13.Best estimate of 59 × 74? (a) 42000 (b) 420 (c) 4200
  14. 14.Best estimate of 333 + 776? (a) 1300 (b) 1100 (c) 900
  15. 15.Best estimate of 80 × 12? (a) 8000 (b) 80 (c) 800
  16. 16.Best estimate of 639 + 330? (a) 1100 (b) 700 (c) 900
  17. 17.Best estimate of 418 + 793? (a) 1000 (b) 1200 (c) 1400
  18. 18.Best estimate of 29 × 39? (a) 1200 (b) 120 (c) 12000
  19. 19.Best estimate of 312 + 171? (a) 700 (b) 500 (c) 300
  20. 20.Best estimate of 73 × 36? (a) 280 (b) 2800 (c) 28000
  21. 21.Best estimate of 577 + 470? (a) 1100 (b) 1300 (c) 900
  22. 22.Best estimate of 370 + 712? (a) 1300 (b) 1100 (c) 900
  23. 23.Best estimate of 60 × 36? (a) 24000 (b) 240 (c) 2400
  24. 24.Best estimate of 497 + 290? (a) 600 (b) 800 (c) 1000
  25. 25.Best estimate of 672 + 326? (a) 1000 (b) 800 (c) 1200
  26. 26.Best estimate of 368 + 247? (a) 400 (b) 600 (c) 800
  27. 27.Best estimate of 625 + 175? (a) 800 (b) 600 (c) 1000
  28. 28.Best estimate of 694 + 632? (a) 1300 (b) 1100 (c) 1500
  29. 29.Best estimate of 66 × 98? (a) 700 (b) 70000 (c) 7000
  30. 30.Best estimate of 30 × 50? (a) 1500 (b) 150 (c) 15000
  31. 31.Best estimate of 281 + 191? (a) 300 (b) 700 (c) 500
  32. 32.Best estimate of 128 + 290? (a) 600 (b) 400 (c) 200
  33. 33.Best estimate of 49 × 21? (a) 1000 (b) 100 (c) 10000
  34. 34.Best estimate of 72 × 30? (a) 21000 (b) 210 (c) 2100
  35. 35.Best estimate of 563 + 676? (a) 1300 (b) 1500 (c) 1100
  36. 36.Best estimate of 20 × 84? (a) 1600 (b) 160 (c) 16000
  37. 37.Best estimate of 38 × 72? (a) 2800 (b) 280 (c) 28000
  38. 38.Best estimate of 70 × 41? (a) 28000 (b) 2800 (c) 280
  39. 39.Best estimate of 28 × 86? (a) 270 (b) 2700 (c) 27000
  40. 40.Best estimate of 80 × 63? (a) 480 (b) 48000 (c) 4800

Answer key

  1. 700
  2. 700
  3. 1400
  4. 800
  5. 1400
  6. 700
  7. 1200
  8. 1300
  9. 6300
  10. 900
  11. 1700
  12. 1100
  13. 4200
  14. 1100
  15. 800
  16. 900
  17. 1200
  18. 1200
  19. 500
  20. 2800
  21. 1100
  22. 1100
  23. 2400
  24. 800
  25. 1000
  26. 600
  27. 800
  28. 1300
  29. 7000
  30. 1500
  31. 500
  32. 400
  33. 1000
  34. 2100
  35. 1300
  36. 1600
  37. 2800
  38. 2800
  39. 2700
  40. 4800

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