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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 884 · 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 16 × 18? (a) 400 (b) 40 (c) 4000
  2. 2.Best estimate of 23 × 42? (a) 800 (b) 8000 (c) 80
  3. 3.Best estimate of 127 + 504? (a) 800 (b) 400 (c) 600
  4. 4.Best estimate of 81 × 91? (a) 7200 (b) 72000 (c) 720
  5. 5.Best estimate of 603 + 561? (a) 1400 (b) 1200 (c) 1000
  6. 6.Best estimate of 729 + 847? (a) 1300 (b) 1700 (c) 1500
  7. 7.Best estimate of 847 + 554? (a) 1200 (b) 1600 (c) 1400
  8. 8.Best estimate of 872 + 779? (a) 1500 (b) 1900 (c) 1700
  9. 9.Best estimate of 17 × 97? (a) 20000 (b) 200 (c) 2000
  10. 10.Best estimate of 60 × 53? (a) 3000 (b) 300 (c) 30000
  11. 11.Best estimate of 24 × 96? (a) 2000 (b) 200 (c) 20000
  12. 12.Best estimate of 558 + 837? (a) 1600 (b) 1400 (c) 1200
  13. 13.Best estimate of 382 + 593? (a) 1000 (b) 1200 (c) 800
  14. 14.Best estimate of 679 + 172? (a) 1100 (b) 700 (c) 900
  15. 15.Best estimate of 263 + 810? (a) 900 (b) 1300 (c) 1100
  16. 16.Best estimate of 772 + 487? (a) 1300 (b) 1100 (c) 1500
  17. 17.Best estimate of 26 × 18? (a) 6000 (b) 600 (c) 60
  18. 18.Best estimate of 124 + 263? (a) 400 (b) 200 (c) 600
  19. 19.Best estimate of 36 × 56? (a) 24000 (b) 240 (c) 2400
  20. 20.Best estimate of 788 + 538? (a) 1500 (b) 1300 (c) 1100
  21. 21.Best estimate of 277 + 628? (a) 900 (b) 1100 (c) 700
  22. 22.Best estimate of 26 × 87? (a) 2700 (b) 27000 (c) 270
  23. 23.Best estimate of 276 + 811? (a) 1300 (b) 1100 (c) 900
  24. 24.Best estimate of 37 × 64? (a) 2400 (b) 240 (c) 24000
  25. 25.Best estimate of 32 × 39? (a) 120 (b) 12000 (c) 1200
  26. 26.Best estimate of 44 × 72? (a) 280 (b) 2800 (c) 28000
  27. 27.Best estimate of 563 + 513? (a) 1300 (b) 900 (c) 1100
  28. 28.Best estimate of 43 × 59? (a) 2400 (b) 24000 (c) 240
  29. 29.Best estimate of 98 × 40? (a) 4000 (b) 40000 (c) 400
  30. 30.Best estimate of 747 + 441? (a) 900 (b) 1100 (c) 1300
  31. 31.Best estimate of 20 × 26? (a) 6000 (b) 600 (c) 60
  32. 32.Best estimate of 321 + 798? (a) 1100 (b) 1300 (c) 900
  33. 33.Best estimate of 18 × 94? (a) 180 (b) 1800 (c) 18000
  34. 34.Best estimate of 581 + 148? (a) 700 (b) 900 (c) 500
  35. 35.Best estimate of 759 + 519? (a) 1500 (b) 1100 (c) 1300
  36. 36.Best estimate of 36 × 17? (a) 8000 (b) 800 (c) 80
  37. 37.Best estimate of 371 + 651? (a) 900 (b) 1300 (c) 1100
  38. 38.Best estimate of 230 + 120? (a) 100 (b) 500 (c) 300
  39. 39.Best estimate of 47 × 87? (a) 450 (b) 45000 (c) 4500
  40. 40.Best estimate of 42 × 67? (a) 280 (b) 2800 (c) 28000

Answer key

  1. 400
  2. 800
  3. 600
  4. 7200
  5. 1200
  6. 1500
  7. 1400
  8. 1700
  9. 2000
  10. 3000
  11. 2000
  12. 1400
  13. 1000
  14. 900
  15. 1100
  16. 1300
  17. 600
  18. 400
  19. 2400
  20. 1300
  21. 900
  22. 2700
  23. 1100
  24. 2400
  25. 1200
  26. 2800
  27. 1100
  28. 2400
  29. 4000
  30. 1100
  31. 600
  32. 1100
  33. 1800
  34. 700
  35. 1300
  36. 800
  37. 1100
  38. 300
  39. 4500
  40. 2800

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