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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 409 · 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 346 + 725? (a) 1000 (b) 800 (c) 1200
  2. 2.Best estimate of 514 + 159? (a) 500 (b) 900 (c) 700
  3. 3.Best estimate of 875 + 328? (a) 1400 (b) 1200 (c) 1000
  4. 4.Best estimate of 774 + 159? (a) 800 (b) 1000 (c) 1200
  5. 5.Best estimate of 515 + 275? (a) 1000 (b) 600 (c) 800
  6. 6.Best estimate of 171 + 379? (a) 400 (b) 600 (c) 800
  7. 7.Best estimate of 720 + 145? (a) 600 (b) 800 (c) 1000
  8. 8.Best estimate of 724 + 645? (a) 1300 (b) 1500 (c) 1100
  9. 9.Best estimate of 209 + 664? (a) 900 (b) 1100 (c) 700
  10. 10.Best estimate of 186 + 751? (a) 1000 (b) 800 (c) 1200
  11. 11.Best estimate of 74 × 74? (a) 49000 (b) 490 (c) 4900
  12. 12.Best estimate of 19 × 66? (a) 1400 (b) 14000 (c) 140
  13. 13.Best estimate of 803 + 669? (a) 1500 (b) 1700 (c) 1300
  14. 14.Best estimate of 13 × 87? (a) 90 (b) 900 (c) 9000
  15. 15.Best estimate of 90 × 16? (a) 1800 (b) 18000 (c) 180
  16. 16.Best estimate of 21 × 20? (a) 40 (b) 4000 (c) 400
  17. 17.Best estimate of 93 × 26? (a) 2700 (b) 27000 (c) 270
  18. 18.Best estimate of 54 × 74? (a) 350 (b) 35000 (c) 3500
  19. 19.Best estimate of 26 × 84? (a) 240 (b) 24000 (c) 2400
  20. 20.Best estimate of 423 + 811? (a) 1400 (b) 1000 (c) 1200
  21. 21.Best estimate of 728 + 365? (a) 900 (b) 1300 (c) 1100
  22. 22.Best estimate of 12 × 16? (a) 20 (b) 200 (c) 2000
  23. 23.Best estimate of 314 + 588? (a) 1100 (b) 900 (c) 700
  24. 24.Best estimate of 410 + 483? (a) 700 (b) 1100 (c) 900
  25. 25.Best estimate of 833 + 872? (a) 1500 (b) 1700 (c) 1900
  26. 26.Best estimate of 96 × 23? (a) 2000 (b) 20000 (c) 200
  27. 27.Best estimate of 33 × 96? (a) 3000 (b) 30000 (c) 300
  28. 28.Best estimate of 789 + 768? (a) 1600 (b) 1400 (c) 1800
  29. 29.Best estimate of 27 × 64? (a) 180 (b) 1800 (c) 18000
  30. 30.Best estimate of 572 + 795? (a) 1600 (b) 1400 (c) 1200
  31. 31.Best estimate of 348 + 195? (a) 500 (b) 700 (c) 300
  32. 32.Best estimate of 812 + 214? (a) 800 (b) 1200 (c) 1000
  33. 33.Best estimate of 229 + 608? (a) 1000 (b) 800 (c) 600
  34. 34.Best estimate of 20 × 27? (a) 600 (b) 60 (c) 6000
  35. 35.Best estimate of 684 + 533? (a) 1400 (b) 1200 (c) 1000
  36. 36.Best estimate of 23 × 86? (a) 180 (b) 18000 (c) 1800
  37. 37.Best estimate of 546 + 707? (a) 1200 (b) 1000 (c) 1400
  38. 38.Best estimate of 831 + 484? (a) 1100 (b) 1500 (c) 1300
  39. 39.Best estimate of 369 + 720? (a) 900 (b) 1100 (c) 1300
  40. 40.Best estimate of 49 × 71? (a) 35000 (b) 3500 (c) 350

Answer key

  1. 1000
  2. 700
  3. 1200
  4. 1000
  5. 800
  6. 600
  7. 800
  8. 1300
  9. 900
  10. 1000
  11. 4900
  12. 1400
  13. 1500
  14. 900
  15. 1800
  16. 400
  17. 2700
  18. 3500
  19. 2400
  20. 1200
  21. 1100
  22. 200
  23. 900
  24. 900
  25. 1700
  26. 2000
  27. 3000
  28. 1600
  29. 1800
  30. 1400
  31. 500
  32. 1000
  33. 800
  34. 600
  35. 1200
  36. 1800
  37. 1200
  38. 1300
  39. 1100
  40. 3500

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