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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 165 · 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 753 + 531? (a) 1500 (b) 1100 (c) 1300
  2. 2.Best estimate of 370 + 244? (a) 600 (b) 400 (c) 800
  3. 3.Best estimate of 37 × 78? (a) 3200 (b) 320 (c) 32000
  4. 4.Best estimate of 566 + 434? (a) 1200 (b) 800 (c) 1000
  5. 5.Best estimate of 78 × 31? (a) 2400 (b) 240 (c) 24000
  6. 6.Best estimate of 569 + 713? (a) 1500 (b) 1100 (c) 1300
  7. 7.Best estimate of 288 + 658? (a) 800 (b) 1200 (c) 1000
  8. 8.Best estimate of 86 × 26? (a) 270 (b) 27000 (c) 2700
  9. 9.Best estimate of 585 + 219? (a) 1000 (b) 600 (c) 800
  10. 10.Best estimate of 551 + 796? (a) 1600 (b) 1400 (c) 1200
  11. 11.Best estimate of 228 + 649? (a) 600 (b) 1000 (c) 800
  12. 12.Best estimate of 405 + 353? (a) 1000 (b) 800 (c) 600
  13. 13.Best estimate of 268 + 389? (a) 900 (b) 700 (c) 500
  14. 14.Best estimate of 532 + 503? (a) 1200 (b) 1000 (c) 800
  15. 15.Best estimate of 90 × 29? (a) 2700 (b) 270 (c) 27000
  16. 16.Best estimate of 863 + 399? (a) 1500 (b) 1300 (c) 1100
  17. 17.Best estimate of 98 × 48? (a) 50000 (b) 5000 (c) 500
  18. 18.Best estimate of 56 × 27? (a) 180 (b) 18000 (c) 1800
  19. 19.Best estimate of 88 × 32? (a) 2700 (b) 27000 (c) 270
  20. 20.Best estimate of 246 + 729? (a) 1100 (b) 700 (c) 900
  21. 21.Best estimate of 719 + 737? (a) 1400 (b) 1600 (c) 1200
  22. 22.Best estimate of 70 × 13? (a) 7000 (b) 700 (c) 70
  23. 23.Best estimate of 260 + 551? (a) 900 (b) 1100 (c) 700
  24. 24.Best estimate of 16 × 88? (a) 180 (b) 1800 (c) 18000
  25. 25.Best estimate of 568 + 831? (a) 1400 (b) 1600 (c) 1200
  26. 26.Best estimate of 312 + 437? (a) 500 (b) 700 (c) 900
  27. 27.Best estimate of 26 × 92? (a) 27000 (b) 270 (c) 2700
  28. 28.Best estimate of 437 + 414? (a) 800 (b) 1000 (c) 600
  29. 29.Best estimate of 74 × 54? (a) 350 (b) 35000 (c) 3500
  30. 30.Best estimate of 179 + 175? (a) 200 (b) 600 (c) 400
  31. 31.Best estimate of 86 × 12? (a) 900 (b) 9000 (c) 90
  32. 32.Best estimate of 16 × 68? (a) 1400 (b) 140 (c) 14000
  33. 33.Best estimate of 58 × 44? (a) 24000 (b) 2400 (c) 240
  34. 34.Best estimate of 283 + 162? (a) 700 (b) 500 (c) 300
  35. 35.Best estimate of 252 + 367? (a) 500 (b) 900 (c) 700
  36. 36.Best estimate of 43 × 23? (a) 800 (b) 80 (c) 8000
  37. 37.Best estimate of 608 + 378? (a) 1000 (b) 800 (c) 1200
  38. 38.Best estimate of 224 + 551? (a) 1000 (b) 800 (c) 600
  39. 39.Best estimate of 29 × 58? (a) 180 (b) 18000 (c) 1800
  40. 40.Best estimate of 63 × 90? (a) 5400 (b) 54000 (c) 540

Answer key

  1. 1300
  2. 600
  3. 3200
  4. 1000
  5. 2400
  6. 1300
  7. 1000
  8. 2700
  9. 800
  10. 1400
  11. 800
  12. 800
  13. 700
  14. 1000
  15. 2700
  16. 1300
  17. 5000
  18. 1800
  19. 2700
  20. 900
  21. 1400
  22. 700
  23. 900
  24. 1800
  25. 1400
  26. 700
  27. 2700
  28. 800
  29. 3500
  30. 400
  31. 900
  32. 1400
  33. 2400
  34. 500
  35. 700
  36. 800
  37. 1000
  38. 800
  39. 1800
  40. 5400

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