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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 300 · 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 × 90? (a) 360 (b) 36000 (c) 3600
  2. 2.Best estimate of 433 + 294? (a) 500 (b) 900 (c) 700
  3. 3.Best estimate of 92 × 96? (a) 9000 (b) 90000 (c) 900
  4. 4.Best estimate of 47 × 43? (a) 20000 (b) 200 (c) 2000
  5. 5.Best estimate of 31 × 41? (a) 1200 (b) 120 (c) 12000
  6. 6.Best estimate of 398 + 280? (a) 500 (b) 900 (c) 700
  7. 7.Best estimate of 199 + 462? (a) 500 (b) 700 (c) 900
  8. 8.Best estimate of 829 + 282? (a) 900 (b) 1100 (c) 1300
  9. 9.Best estimate of 254 + 653? (a) 1200 (b) 1000 (c) 800
  10. 10.Best estimate of 485 + 455? (a) 1200 (b) 1000 (c) 800
  11. 11.Best estimate of 38 × 31? (a) 1200 (b) 12000 (c) 120
  12. 12.Best estimate of 420 + 283? (a) 900 (b) 500 (c) 700
  13. 13.Best estimate of 623 + 700? (a) 1300 (b) 1100 (c) 1500
  14. 14.Best estimate of 70 × 77? (a) 560 (b) 56000 (c) 5600
  15. 15.Best estimate of 92 × 57? (a) 540 (b) 54000 (c) 5400
  16. 16.Best estimate of 33 × 70? (a) 2100 (b) 21000 (c) 210
  17. 17.Best estimate of 459 + 868? (a) 1400 (b) 1200 (c) 1600
  18. 18.Best estimate of 90 × 32? (a) 2700 (b) 270 (c) 27000
  19. 19.Best estimate of 172 + 864? (a) 900 (b) 1100 (c) 1300
  20. 20.Best estimate of 224 + 359? (a) 800 (b) 600 (c) 400
  21. 21.Best estimate of 880 + 879? (a) 1600 (b) 2000 (c) 1800
  22. 22.Best estimate of 178 + 411? (a) 800 (b) 600 (c) 400
  23. 23.Best estimate of 230 + 180? (a) 200 (b) 400 (c) 600
  24. 24.Best estimate of 90 × 28? (a) 270 (b) 2700 (c) 27000
  25. 25.Best estimate of 86 × 14? (a) 9000 (b) 900 (c) 90
  26. 26.Best estimate of 82 × 76? (a) 6400 (b) 64000 (c) 640
  27. 27.Best estimate of 458 + 429? (a) 1100 (b) 700 (c) 900
  28. 28.Best estimate of 17 × 54? (a) 10000 (b) 100 (c) 1000
  29. 29.Best estimate of 148 + 196? (a) 100 (b) 500 (c) 300
  30. 30.Best estimate of 260 + 799? (a) 1100 (b) 1300 (c) 900
  31. 31.Best estimate of 494 + 243? (a) 700 (b) 900 (c) 500
  32. 32.Best estimate of 96 × 63? (a) 6000 (b) 60000 (c) 600
  33. 33.Best estimate of 47 × 97? (a) 5000 (b) 500 (c) 50000
  34. 34.Best estimate of 86 × 44? (a) 36000 (b) 3600 (c) 360
  35. 35.Best estimate of 814 + 395? (a) 1200 (b) 1000 (c) 1400
  36. 36.Best estimate of 644 + 563? (a) 1000 (b) 1400 (c) 1200
  37. 37.Best estimate of 84 × 29? (a) 24000 (b) 240 (c) 2400
  38. 38.Best estimate of 48 × 76? (a) 40000 (b) 4000 (c) 400
  39. 39.Best estimate of 83 × 12? (a) 800 (b) 80 (c) 8000
  40. 40.Best estimate of 19 × 63? (a) 12000 (b) 120 (c) 1200

Answer key

  1. 3600
  2. 700
  3. 9000
  4. 2000
  5. 1200
  6. 700
  7. 700
  8. 1100
  9. 1000
  10. 1000
  11. 1200
  12. 700
  13. 1300
  14. 5600
  15. 5400
  16. 2100
  17. 1400
  18. 2700
  19. 1100
  20. 600
  21. 1800
  22. 600
  23. 400
  24. 2700
  25. 900
  26. 6400
  27. 900
  28. 1000
  29. 300
  30. 1100
  31. 700
  32. 6000
  33. 5000
  34. 3600
  35. 1200
  36. 1200
  37. 2400
  38. 4000
  39. 800
  40. 1200

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