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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 393 · 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 339 + 190? (a) 300 (b) 500 (c) 700
  2. 2.Best estimate of 192 + 453? (a) 900 (b) 500 (c) 700
  3. 3.Best estimate of 46 × 23? (a) 10000 (b) 1000 (c) 100
  4. 4.Best estimate of 831 + 148? (a) 700 (b) 900 (c) 1100
  5. 5.Best estimate of 616 + 206? (a) 800 (b) 600 (c) 1000
  6. 6.Best estimate of 653 + 852? (a) 1400 (b) 1800 (c) 1600
  7. 7.Best estimate of 56 × 92? (a) 54000 (b) 540 (c) 5400
  8. 8.Best estimate of 497 + 189? (a) 900 (b) 500 (c) 700
  9. 9.Best estimate of 313 + 120? (a) 400 (b) 600 (c) 200
  10. 10.Best estimate of 57 × 30? (a) 180 (b) 18000 (c) 1800
  11. 11.Best estimate of 36 × 43? (a) 16000 (b) 1600 (c) 160
  12. 12.Best estimate of 46 × 13? (a) 5000 (b) 500 (c) 50
  13. 13.Best estimate of 69 × 28? (a) 21000 (b) 2100 (c) 210
  14. 14.Best estimate of 66 × 13? (a) 70 (b) 700 (c) 7000
  15. 15.Best estimate of 813 + 756? (a) 1400 (b) 1800 (c) 1600
  16. 16.Best estimate of 316 + 479? (a) 600 (b) 800 (c) 1000
  17. 17.Best estimate of 26 × 40? (a) 1200 (b) 12000 (c) 120
  18. 18.Best estimate of 41 × 12? (a) 40 (b) 4000 (c) 400
  19. 19.Best estimate of 86 × 27? (a) 270 (b) 27000 (c) 2700
  20. 20.Best estimate of 823 + 542? (a) 1100 (b) 1500 (c) 1300
  21. 21.Best estimate of 612 + 573? (a) 1000 (b) 1400 (c) 1200
  22. 22.Best estimate of 22 × 88? (a) 18000 (b) 180 (c) 1800
  23. 23.Best estimate of 86 × 91? (a) 8100 (b) 810 (c) 81000
  24. 24.Best estimate of 183 + 681? (a) 900 (b) 700 (c) 1100
  25. 25.Best estimate of 92 × 23? (a) 18000 (b) 180 (c) 1800
  26. 26.Best estimate of 63 × 94? (a) 54000 (b) 5400 (c) 540
  27. 27.Best estimate of 395 + 681? (a) 1300 (b) 1100 (c) 900
  28. 28.Best estimate of 254 + 260? (a) 400 (b) 600 (c) 800
  29. 29.Best estimate of 626 + 551? (a) 1200 (b) 1000 (c) 1400
  30. 30.Best estimate of 196 + 469? (a) 500 (b) 900 (c) 700
  31. 31.Best estimate of 56 × 29? (a) 1800 (b) 18000 (c) 180
  32. 32.Best estimate of 76 × 72? (a) 56000 (b) 560 (c) 5600
  33. 33.Best estimate of 69 × 69? (a) 4900 (b) 49000 (c) 490
  34. 34.Best estimate of 851 + 719? (a) 1600 (b) 1800 (c) 1400
  35. 35.Best estimate of 90 × 23? (a) 1800 (b) 18000 (c) 180
  36. 36.Best estimate of 225 + 673? (a) 700 (b) 1100 (c) 900
  37. 37.Best estimate of 420 + 733? (a) 1100 (b) 900 (c) 1300
  38. 38.Best estimate of 737 + 644? (a) 1500 (b) 1300 (c) 1100
  39. 39.Best estimate of 305 + 451? (a) 600 (b) 1000 (c) 800
  40. 40.Best estimate of 53 × 26? (a) 1500 (b) 15000 (c) 150

Answer key

  1. 500
  2. 700
  3. 1000
  4. 900
  5. 800
  6. 1600
  7. 5400
  8. 700
  9. 400
  10. 1800
  11. 1600
  12. 500
  13. 2100
  14. 700
  15. 1600
  16. 800
  17. 1200
  18. 400
  19. 2700
  20. 1300
  21. 1200
  22. 1800
  23. 8100
  24. 900
  25. 1800
  26. 5400
  27. 1100
  28. 600
  29. 1200
  30. 700
  31. 1800
  32. 5600
  33. 4900
  34. 1600
  35. 1800
  36. 900
  37. 1100
  38. 1300
  39. 800
  40. 1500

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