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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 288 · 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 758 + 465? (a) 1300 (b) 1500 (c) 1100
  2. 2.Best estimate of 76 × 73? (a) 5600 (b) 560 (c) 56000
  3. 3.Best estimate of 68 × 61? (a) 420 (b) 4200 (c) 42000
  4. 4.Best estimate of 704 + 142? (a) 1000 (b) 800 (c) 600
  5. 5.Best estimate of 145 + 751? (a) 900 (b) 700 (c) 1100
  6. 6.Best estimate of 58 × 21? (a) 12000 (b) 1200 (c) 120
  7. 7.Best estimate of 167 + 805? (a) 800 (b) 1000 (c) 1200
  8. 8.Best estimate of 662 + 476? (a) 1000 (b) 1400 (c) 1200
  9. 9.Best estimate of 74 × 92? (a) 630 (b) 63000 (c) 6300
  10. 10.Best estimate of 365 + 545? (a) 700 (b) 1100 (c) 900
  11. 11.Best estimate of 21 × 41? (a) 80 (b) 8000 (c) 800
  12. 12.Best estimate of 78 × 79? (a) 640 (b) 64000 (c) 6400
  13. 13.Best estimate of 17 × 94? (a) 18000 (b) 180 (c) 1800
  14. 14.Best estimate of 89 × 41? (a) 360 (b) 3600 (c) 36000
  15. 15.Best estimate of 736 + 391? (a) 900 (b) 1300 (c) 1100
  16. 16.Best estimate of 42 × 54? (a) 2000 (b) 20000 (c) 200
  17. 17.Best estimate of 704 + 174? (a) 1100 (b) 900 (c) 700
  18. 18.Best estimate of 224 + 445? (a) 800 (b) 600 (c) 400
  19. 19.Best estimate of 833 + 433? (a) 1400 (b) 1200 (c) 1000
  20. 20.Best estimate of 288 + 145? (a) 200 (b) 600 (c) 400
  21. 21.Best estimate of 513 + 689? (a) 1200 (b) 1000 (c) 1400
  22. 22.Best estimate of 70 × 84? (a) 5600 (b) 560 (c) 56000
  23. 23.Best estimate of 16 × 38? (a) 80 (b) 8000 (c) 800
  24. 24.Best estimate of 97 × 40? (a) 40000 (b) 4000 (c) 400
  25. 25.Best estimate of 12 × 49? (a) 500 (b) 50 (c) 5000
  26. 26.Best estimate of 432 + 489? (a) 900 (b) 1100 (c) 700
  27. 27.Best estimate of 38 × 79? (a) 320 (b) 32000 (c) 3200
  28. 28.Best estimate of 79 × 14? (a) 80 (b) 800 (c) 8000
  29. 29.Best estimate of 93 × 59? (a) 54000 (b) 5400 (c) 540
  30. 30.Best estimate of 67 × 72? (a) 4900 (b) 49000 (c) 490
  31. 31.Best estimate of 486 + 397? (a) 1100 (b) 900 (c) 700
  32. 32.Best estimate of 227 + 461? (a) 700 (b) 900 (c) 500
  33. 33.Best estimate of 38 × 64? (a) 24000 (b) 2400 (c) 240
  34. 34.Best estimate of 61 × 47? (a) 300 (b) 3000 (c) 30000
  35. 35.Best estimate of 57 × 56? (a) 360 (b) 3600 (c) 36000
  36. 36.Best estimate of 260 + 557? (a) 700 (b) 900 (c) 1100
  37. 37.Best estimate of 295 + 258? (a) 600 (b) 400 (c) 800
  38. 38.Best estimate of 21 × 12? (a) 2000 (b) 200 (c) 20
  39. 39.Best estimate of 401 + 407? (a) 800 (b) 1000 (c) 600
  40. 40.Best estimate of 261 + 176? (a) 700 (b) 500 (c) 300

Answer key

  1. 1300
  2. 5600
  3. 4200
  4. 800
  5. 900
  6. 1200
  7. 1000
  8. 1200
  9. 6300
  10. 900
  11. 800
  12. 6400
  13. 1800
  14. 3600
  15. 1100
  16. 2000
  17. 900
  18. 600
  19. 1200
  20. 400
  21. 1200
  22. 5600
  23. 800
  24. 4000
  25. 500
  26. 900
  27. 3200
  28. 800
  29. 5400
  30. 4900
  31. 900
  32. 700
  33. 2400
  34. 3000
  35. 3600
  36. 900
  37. 600
  38. 200
  39. 800
  40. 500

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