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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 665 · 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 81 × 91? (a) 7200 (b) 720 (c) 72000
  2. 2.Best estimate of 20 × 76? (a) 1600 (b) 160 (c) 16000
  3. 3.Best estimate of 56 × 23? (a) 1200 (b) 12000 (c) 120
  4. 4.Best estimate of 368 + 191? (a) 400 (b) 600 (c) 800
  5. 5.Best estimate of 28 × 39? (a) 12000 (b) 120 (c) 1200
  6. 6.Best estimate of 57 × 53? (a) 3000 (b) 300 (c) 30000
  7. 7.Best estimate of 326 + 788? (a) 1100 (b) 1300 (c) 900
  8. 8.Best estimate of 657 + 284? (a) 1200 (b) 800 (c) 1000
  9. 9.Best estimate of 136 + 470? (a) 400 (b) 800 (c) 600
  10. 10.Best estimate of 30 × 48? (a) 15000 (b) 150 (c) 1500
  11. 11.Best estimate of 768 + 442? (a) 1200 (b) 1400 (c) 1000
  12. 12.Best estimate of 93 × 72? (a) 63000 (b) 6300 (c) 630
  13. 13.Best estimate of 751 + 779? (a) 1600 (b) 1400 (c) 1800
  14. 14.Best estimate of 437 + 824? (a) 1400 (b) 1000 (c) 1200
  15. 15.Best estimate of 675 + 853? (a) 1600 (b) 1400 (c) 1800
  16. 16.Best estimate of 145 + 475? (a) 600 (b) 400 (c) 800
  17. 17.Best estimate of 644 + 384? (a) 1200 (b) 800 (c) 1000
  18. 18.Best estimate of 51 × 63? (a) 3000 (b) 30000 (c) 300
  19. 19.Best estimate of 87 × 39? (a) 3600 (b) 360 (c) 36000
  20. 20.Best estimate of 335 + 305? (a) 600 (b) 400 (c) 800
  21. 21.Best estimate of 28 × 93? (a) 2700 (b) 27000 (c) 270
  22. 22.Best estimate of 90 × 94? (a) 8100 (b) 810 (c) 81000
  23. 23.Best estimate of 87 × 76? (a) 72000 (b) 720 (c) 7200
  24. 24.Best estimate of 94 × 53? (a) 4500 (b) 450 (c) 45000
  25. 25.Best estimate of 36 × 32? (a) 12000 (b) 1200 (c) 120
  26. 26.Best estimate of 685 + 802? (a) 1500 (b) 1700 (c) 1300
  27. 27.Best estimate of 216 + 140? (a) 500 (b) 300 (c) 100
  28. 28.Best estimate of 271 + 288? (a) 600 (b) 800 (c) 400
  29. 29.Best estimate of 307 + 609? (a) 700 (b) 1100 (c) 900
  30. 30.Best estimate of 664 + 627? (a) 1500 (b) 1300 (c) 1100
  31. 31.Best estimate of 653 + 222? (a) 700 (b) 1100 (c) 900
  32. 32.Best estimate of 448 + 370? (a) 600 (b) 1000 (c) 800
  33. 33.Best estimate of 159 + 120? (a) 300 (b) 100 (c) 500
  34. 34.Best estimate of 67 × 13? (a) 700 (b) 7000 (c) 70
  35. 35.Best estimate of 631 + 285? (a) 900 (b) 700 (c) 1100
  36. 36.Best estimate of 272 + 651? (a) 800 (b) 1000 (c) 1200
  37. 37.Best estimate of 36 × 92? (a) 3600 (b) 36000 (c) 360
  38. 38.Best estimate of 76 × 59? (a) 48000 (b) 4800 (c) 480
  39. 39.Best estimate of 306 + 367? (a) 500 (b) 900 (c) 700
  40. 40.Best estimate of 868 + 437? (a) 1300 (b) 1100 (c) 1500

Answer key

  1. 7200
  2. 1600
  3. 1200
  4. 600
  5. 1200
  6. 3000
  7. 1100
  8. 1000
  9. 600
  10. 1500
  11. 1200
  12. 6300
  13. 1600
  14. 1200
  15. 1600
  16. 600
  17. 1000
  18. 3000
  19. 3600
  20. 600
  21. 2700
  22. 8100
  23. 7200
  24. 4500
  25. 1200
  26. 1500
  27. 300
  28. 600
  29. 900
  30. 1300
  31. 900
  32. 800
  33. 300
  34. 700
  35. 900
  36. 1000
  37. 3600
  38. 4800
  39. 700
  40. 1300

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