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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 985 · 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 431 + 443? (a) 800 (b) 600 (c) 1000
  2. 2.Best estimate of 88 × 40? (a) 36000 (b) 3600 (c) 360
  3. 3.Best estimate of 608 + 770? (a) 1400 (b) 1200 (c) 1600
  4. 4.Best estimate of 84 × 24? (a) 1600 (b) 160 (c) 16000
  5. 5.Best estimate of 737 + 721? (a) 1400 (b) 1600 (c) 1200
  6. 6.Best estimate of 244 + 461? (a) 500 (b) 900 (c) 700
  7. 7.Best estimate of 66 × 38? (a) 28000 (b) 2800 (c) 280
  8. 8.Best estimate of 82 × 70? (a) 560 (b) 56000 (c) 5600
  9. 9.Best estimate of 50 × 46? (a) 25000 (b) 2500 (c) 250
  10. 10.Best estimate of 523 + 401? (a) 900 (b) 1100 (c) 700
  11. 11.Best estimate of 29 × 26? (a) 900 (b) 90 (c) 9000
  12. 12.Best estimate of 84 × 16? (a) 1600 (b) 16000 (c) 160
  13. 13.Best estimate of 228 + 743? (a) 1100 (b) 900 (c) 700
  14. 14.Best estimate of 464 + 217? (a) 500 (b) 900 (c) 700
  15. 15.Best estimate of 69 × 47? (a) 3500 (b) 35000 (c) 350
  16. 16.Best estimate of 814 + 619? (a) 1600 (b) 1200 (c) 1400
  17. 17.Best estimate of 348 + 223? (a) 700 (b) 500 (c) 300
  18. 18.Best estimate of 98 × 96? (a) 1000 (b) 100000 (c) 10000
  19. 19.Best estimate of 403 + 204? (a) 600 (b) 800 (c) 400
  20. 20.Best estimate of 88 × 17? (a) 1800 (b) 180 (c) 18000
  21. 21.Best estimate of 462 + 219? (a) 500 (b) 700 (c) 900
  22. 22.Best estimate of 60 × 12? (a) 600 (b) 6000 (c) 60
  23. 23.Best estimate of 149 + 708? (a) 1000 (b) 800 (c) 600
  24. 24.Best estimate of 24 × 66? (a) 140 (b) 14000 (c) 1400
  25. 25.Best estimate of 61 × 34? (a) 1800 (b) 18000 (c) 180
  26. 26.Best estimate of 585 + 148? (a) 500 (b) 700 (c) 900
  27. 27.Best estimate of 96 × 37? (a) 400 (b) 4000 (c) 40000
  28. 28.Best estimate of 16 × 47? (a) 1000 (b) 100 (c) 10000
  29. 29.Best estimate of 221 + 763? (a) 1000 (b) 1200 (c) 800
  30. 30.Best estimate of 176 + 532? (a) 900 (b) 500 (c) 700
  31. 31.Best estimate of 817 + 183? (a) 1200 (b) 800 (c) 1000
  32. 32.Best estimate of 715 + 304? (a) 1200 (b) 800 (c) 1000
  33. 33.Best estimate of 43 × 94? (a) 3600 (b) 36000 (c) 360
  34. 34.Best estimate of 23 × 66? (a) 140 (b) 14000 (c) 1400
  35. 35.Best estimate of 38 × 51? (a) 2000 (b) 20000 (c) 200
  36. 36.Best estimate of 29 × 79? (a) 24000 (b) 2400 (c) 240
  37. 37.Best estimate of 580 + 578? (a) 1000 (b) 1200 (c) 1400
  38. 38.Best estimate of 454 + 639? (a) 1300 (b) 1100 (c) 900
  39. 39.Best estimate of 32 × 96? (a) 3000 (b) 30000 (c) 300
  40. 40.Best estimate of 96 × 51? (a) 5000 (b) 50000 (c) 500

Answer key

  1. 800
  2. 3600
  3. 1400
  4. 1600
  5. 1400
  6. 700
  7. 2800
  8. 5600
  9. 2500
  10. 900
  11. 900
  12. 1600
  13. 900
  14. 700
  15. 3500
  16. 1400
  17. 500
  18. 10000
  19. 600
  20. 1800
  21. 700
  22. 600
  23. 800
  24. 1400
  25. 1800
  26. 700
  27. 4000
  28. 1000
  29. 1000
  30. 700
  31. 1000
  32. 1000
  33. 3600
  34. 1400
  35. 2000
  36. 2400
  37. 1200
  38. 1100
  39. 3000
  40. 5000

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