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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 540 · 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 36 × 12? (a) 4000 (b) 40 (c) 400
  2. 2.Best estimate of 143 + 677? (a) 800 (b) 600 (c) 1000
  3. 3.Best estimate of 50 × 16? (a) 1000 (b) 10000 (c) 100
  4. 4.Best estimate of 151 + 610? (a) 600 (b) 1000 (c) 800
  5. 5.Best estimate of 305 + 870? (a) 1400 (b) 1000 (c) 1200
  6. 6.Best estimate of 407 + 421? (a) 800 (b) 600 (c) 1000
  7. 7.Best estimate of 695 + 218? (a) 700 (b) 1100 (c) 900
  8. 8.Best estimate of 461 + 475? (a) 800 (b) 1200 (c) 1000
  9. 9.Best estimate of 314 + 877? (a) 1200 (b) 1000 (c) 1400
  10. 10.Best estimate of 29 × 42? (a) 120 (b) 12000 (c) 1200
  11. 11.Best estimate of 21 × 39? (a) 80 (b) 8000 (c) 800
  12. 12.Best estimate of 399 + 265? (a) 500 (b) 700 (c) 900
  13. 13.Best estimate of 20 × 87? (a) 180 (b) 1800 (c) 18000
  14. 14.Best estimate of 792 + 602? (a) 1400 (b) 1200 (c) 1600
  15. 15.Best estimate of 288 + 647? (a) 900 (b) 1100 (c) 700
  16. 16.Best estimate of 291 + 487? (a) 600 (b) 1000 (c) 800
  17. 17.Best estimate of 12 × 29? (a) 3000 (b) 30 (c) 300
  18. 18.Best estimate of 76 × 83? (a) 64000 (b) 6400 (c) 640
  19. 19.Best estimate of 29 × 62? (a) 1800 (b) 180 (c) 18000
  20. 20.Best estimate of 537 + 462? (a) 800 (b) 1000 (c) 1200
  21. 21.Best estimate of 48 × 32? (a) 1500 (b) 150 (c) 15000
  22. 22.Best estimate of 36 × 97? (a) 40000 (b) 4000 (c) 400
  23. 23.Best estimate of 207 + 437? (a) 800 (b) 600 (c) 400
  24. 24.Best estimate of 42 × 97? (a) 40000 (b) 4000 (c) 400
  25. 25.Best estimate of 529 + 553? (a) 1100 (b) 1300 (c) 900
  26. 26.Best estimate of 47 × 68? (a) 35000 (b) 3500 (c) 350
  27. 27.Best estimate of 840 + 787? (a) 1600 (b) 1800 (c) 1400
  28. 28.Best estimate of 842 + 728? (a) 1500 (b) 1300 (c) 1700
  29. 29.Best estimate of 36 × 58? (a) 2400 (b) 24000 (c) 240
  30. 30.Best estimate of 17 × 56? (a) 1200 (b) 120 (c) 12000
  31. 31.Best estimate of 42 × 46? (a) 2000 (b) 20000 (c) 200
  32. 32.Best estimate of 59 × 12? (a) 600 (b) 6000 (c) 60
  33. 33.Best estimate of 622 + 154? (a) 600 (b) 1000 (c) 800
  34. 34.Best estimate of 72 × 89? (a) 630 (b) 6300 (c) 63000
  35. 35.Best estimate of 875 + 129? (a) 1200 (b) 1000 (c) 800
  36. 36.Best estimate of 877 + 160? (a) 1100 (b) 1300 (c) 900
  37. 37.Best estimate of 80 × 16? (a) 160 (b) 16000 (c) 1600
  38. 38.Best estimate of 534 + 452? (a) 1200 (b) 1000 (c) 800
  39. 39.Best estimate of 13 × 67? (a) 700 (b) 70 (c) 7000
  40. 40.Best estimate of 36 × 60? (a) 24000 (b) 2400 (c) 240

Answer key

  1. 400
  2. 800
  3. 1000
  4. 800
  5. 1200
  6. 800
  7. 900
  8. 1000
  9. 1200
  10. 1200
  11. 800
  12. 700
  13. 1800
  14. 1400
  15. 900
  16. 800
  17. 300
  18. 6400
  19. 1800
  20. 1000
  21. 1500
  22. 4000
  23. 600
  24. 4000
  25. 1100
  26. 3500
  27. 1600
  28. 1500
  29. 2400
  30. 1200
  31. 2000
  32. 600
  33. 800
  34. 6300
  35. 1000
  36. 1100
  37. 1600
  38. 1000
  39. 700
  40. 2400

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