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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 866 · 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 54 × 18? (a) 10000 (b) 1000 (c) 100
  2. 2.Best estimate of 612 + 443? (a) 1200 (b) 800 (c) 1000
  3. 3.Best estimate of 812 + 801? (a) 1400 (b) 1800 (c) 1600
  4. 4.Best estimate of 19 × 90? (a) 180 (b) 1800 (c) 18000
  5. 5.Best estimate of 659 + 397? (a) 1100 (b) 1300 (c) 900
  6. 6.Best estimate of 454 + 802? (a) 1500 (b) 1300 (c) 1100
  7. 7.Best estimate of 517 + 545? (a) 800 (b) 1000 (c) 1200
  8. 8.Best estimate of 58 × 63? (a) 3600 (b) 360 (c) 36000
  9. 9.Best estimate of 44 × 53? (a) 20000 (b) 2000 (c) 200
  10. 10.Best estimate of 31 × 83? (a) 2400 (b) 24000 (c) 240
  11. 11.Best estimate of 465 + 192? (a) 500 (b) 900 (c) 700
  12. 12.Best estimate of 651 + 660? (a) 1600 (b) 1400 (c) 1200
  13. 13.Best estimate of 24 × 20? (a) 4000 (b) 40 (c) 400
  14. 14.Best estimate of 298 + 851? (a) 1400 (b) 1200 (c) 1000
  15. 15.Best estimate of 419 + 880? (a) 1300 (b) 1100 (c) 1500
  16. 16.Best estimate of 338 + 258? (a) 800 (b) 400 (c) 600
  17. 17.Best estimate of 83 × 76? (a) 6400 (b) 64000 (c) 640
  18. 18.Best estimate of 695 + 126? (a) 800 (b) 600 (c) 1000
  19. 19.Best estimate of 610 + 719? (a) 1100 (b) 1300 (c) 1500
  20. 20.Best estimate of 91 × 80? (a) 720 (b) 7200 (c) 72000
  21. 21.Best estimate of 90 × 48? (a) 4500 (b) 45000 (c) 450
  22. 22.Best estimate of 699 + 729? (a) 1600 (b) 1400 (c) 1200
  23. 23.Best estimate of 379 + 366? (a) 800 (b) 1000 (c) 600
  24. 24.Best estimate of 827 + 639? (a) 1400 (b) 1200 (c) 1600
  25. 25.Best estimate of 36 × 27? (a) 120 (b) 12000 (c) 1200
  26. 26.Best estimate of 377 + 640? (a) 1200 (b) 800 (c) 1000
  27. 27.Best estimate of 336 + 298? (a) 600 (b) 400 (c) 800
  28. 28.Best estimate of 88 × 90? (a) 8100 (b) 810 (c) 81000
  29. 29.Best estimate of 98 × 87? (a) 900 (b) 90000 (c) 9000
  30. 30.Best estimate of 286 + 259? (a) 600 (b) 800 (c) 400
  31. 31.Best estimate of 52 × 52? (a) 2500 (b) 25000 (c) 250
  32. 32.Best estimate of 66 × 86? (a) 63000 (b) 630 (c) 6300
  33. 33.Best estimate of 858 + 409? (a) 1100 (b) 1500 (c) 1300
  34. 34.Best estimate of 451 + 422? (a) 700 (b) 1100 (c) 900
  35. 35.Best estimate of 762 + 185? (a) 1200 (b) 800 (c) 1000
  36. 36.Best estimate of 661 + 430? (a) 1300 (b) 900 (c) 1100
  37. 37.Best estimate of 82 × 42? (a) 32000 (b) 320 (c) 3200
  38. 38.Best estimate of 743 + 207? (a) 900 (b) 1100 (c) 700
  39. 39.Best estimate of 181 + 551? (a) 800 (b) 600 (c) 1000
  40. 40.Best estimate of 83 × 16? (a) 16000 (b) 160 (c) 1600

Answer key

  1. 1000
  2. 1000
  3. 1600
  4. 1800
  5. 1100
  6. 1300
  7. 1000
  8. 3600
  9. 2000
  10. 2400
  11. 700
  12. 1400
  13. 400
  14. 1200
  15. 1300
  16. 600
  17. 6400
  18. 800
  19. 1300
  20. 7200
  21. 4500
  22. 1400
  23. 800
  24. 1400
  25. 1200
  26. 1000
  27. 600
  28. 8100
  29. 9000
  30. 600
  31. 2500
  32. 6300
  33. 1300
  34. 900
  35. 1000
  36. 1100
  37. 3200
  38. 900
  39. 800
  40. 1600

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