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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 180 · 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 754 + 457? (a) 1100 (b) 1300 (c) 1500
  2. 2.Best estimate of 90 × 14? (a) 900 (b) 90 (c) 9000
  3. 3.Best estimate of 81 × 98? (a) 8000 (b) 80000 (c) 800
  4. 4.Best estimate of 269 + 595? (a) 1100 (b) 900 (c) 700
  5. 5.Best estimate of 47 × 51? (a) 250 (b) 25000 (c) 2500
  6. 6.Best estimate of 38 × 20? (a) 8000 (b) 800 (c) 80
  7. 7.Best estimate of 50 × 23? (a) 1000 (b) 10000 (c) 100
  8. 8.Best estimate of 641 + 819? (a) 1400 (b) 1200 (c) 1600
  9. 9.Best estimate of 22 × 24? (a) 40 (b) 400 (c) 4000
  10. 10.Best estimate of 690 + 245? (a) 700 (b) 900 (c) 1100
  11. 11.Best estimate of 36 × 54? (a) 20000 (b) 2000 (c) 200
  12. 12.Best estimate of 247 + 524? (a) 900 (b) 700 (c) 500
  13. 13.Best estimate of 36 × 29? (a) 12000 (b) 120 (c) 1200
  14. 14.Best estimate of 50 × 32? (a) 150 (b) 1500 (c) 15000
  15. 15.Best estimate of 194 + 581? (a) 1000 (b) 800 (c) 600
  16. 16.Best estimate of 88 × 22? (a) 1800 (b) 18000 (c) 180
  17. 17.Best estimate of 668 + 541? (a) 1200 (b) 1000 (c) 1400
  18. 18.Best estimate of 447 + 332? (a) 700 (b) 500 (c) 900
  19. 19.Best estimate of 53 × 26? (a) 1500 (b) 15000 (c) 150
  20. 20.Best estimate of 384 + 209? (a) 400 (b) 800 (c) 600
  21. 21.Best estimate of 53 × 50? (a) 25000 (b) 250 (c) 2500
  22. 22.Best estimate of 449 + 226? (a) 800 (b) 400 (c) 600
  23. 23.Best estimate of 772 + 156? (a) 1200 (b) 800 (c) 1000
  24. 24.Best estimate of 64 × 32? (a) 1800 (b) 180 (c) 18000
  25. 25.Best estimate of 19 × 17? (a) 4000 (b) 40 (c) 400
  26. 26.Best estimate of 366 + 365? (a) 600 (b) 800 (c) 1000
  27. 27.Best estimate of 16 × 40? (a) 80 (b) 8000 (c) 800
  28. 28.Best estimate of 23 × 74? (a) 140 (b) 1400 (c) 14000
  29. 29.Best estimate of 20 × 31? (a) 60 (b) 600 (c) 6000
  30. 30.Best estimate of 835 + 471? (a) 1100 (b) 1300 (c) 1500
  31. 31.Best estimate of 521 + 751? (a) 1500 (b) 1100 (c) 1300
  32. 32.Best estimate of 705 + 740? (a) 1600 (b) 1400 (c) 1200
  33. 33.Best estimate of 39 × 89? (a) 3600 (b) 360 (c) 36000
  34. 34.Best estimate of 29 × 80? (a) 24000 (b) 2400 (c) 240
  35. 35.Best estimate of 56 × 54? (a) 3000 (b) 300 (c) 30000
  36. 36.Best estimate of 69 × 17? (a) 140 (b) 14000 (c) 1400
  37. 37.Best estimate of 617 + 811? (a) 1400 (b) 1200 (c) 1600
  38. 38.Best estimate of 239 + 400? (a) 400 (b) 600 (c) 800
  39. 39.Best estimate of 304 + 351? (a) 700 (b) 500 (c) 900
  40. 40.Best estimate of 419 + 809? (a) 1000 (b) 1200 (c) 1400

Answer key

  1. 1300
  2. 900
  3. 8000
  4. 900
  5. 2500
  6. 800
  7. 1000
  8. 1400
  9. 400
  10. 900
  11. 2000
  12. 700
  13. 1200
  14. 1500
  15. 800
  16. 1800
  17. 1200
  18. 700
  19. 1500
  20. 600
  21. 2500
  22. 600
  23. 1000
  24. 1800
  25. 400
  26. 800
  27. 800
  28. 1400
  29. 600
  30. 1300
  31. 1300
  32. 1400
  33. 3600
  34. 2400
  35. 3000
  36. 1400
  37. 1400
  38. 600
  39. 700
  40. 1200

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