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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 711 · 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 74 × 86? (a) 6300 (b) 63000 (c) 630
  2. 2.Best estimate of 423 + 455? (a) 700 (b) 1100 (c) 900
  3. 3.Best estimate of 359 + 491? (a) 700 (b) 900 (c) 1100
  4. 4.Best estimate of 26 × 87? (a) 270 (b) 2700 (c) 27000
  5. 5.Best estimate of 46 × 33? (a) 15000 (b) 1500 (c) 150
  6. 6.Best estimate of 49 × 49? (a) 25000 (b) 250 (c) 2500
  7. 7.Best estimate of 825 + 581? (a) 1400 (b) 1600 (c) 1200
  8. 8.Best estimate of 804 + 129? (a) 900 (b) 1100 (c) 700
  9. 9.Best estimate of 277 + 677? (a) 1200 (b) 800 (c) 1000
  10. 10.Best estimate of 68 × 63? (a) 42000 (b) 420 (c) 4200
  11. 11.Best estimate of 281 + 125? (a) 600 (b) 200 (c) 400
  12. 12.Best estimate of 716 + 343? (a) 1000 (b) 1200 (c) 800
  13. 13.Best estimate of 803 + 736? (a) 1500 (b) 1300 (c) 1700
  14. 14.Best estimate of 145 + 639? (a) 500 (b) 900 (c) 700
  15. 15.Best estimate of 499 + 329? (a) 800 (b) 1000 (c) 600
  16. 16.Best estimate of 84 × 58? (a) 4800 (b) 480 (c) 48000
  17. 17.Best estimate of 96 × 33? (a) 300 (b) 3000 (c) 30000
  18. 18.Best estimate of 401 + 518? (a) 900 (b) 1100 (c) 700
  19. 19.Best estimate of 475 + 735? (a) 1000 (b) 1200 (c) 1400
  20. 20.Best estimate of 33 × 66? (a) 21000 (b) 2100 (c) 210
  21. 21.Best estimate of 601 + 646? (a) 1200 (b) 1400 (c) 1000
  22. 22.Best estimate of 637 + 513? (a) 1300 (b) 900 (c) 1100
  23. 23.Best estimate of 31 × 94? (a) 27000 (b) 270 (c) 2700
  24. 24.Best estimate of 66 × 97? (a) 7000 (b) 700 (c) 70000
  25. 25.Best estimate of 495 + 657? (a) 1200 (b) 1400 (c) 1000
  26. 26.Best estimate of 624 + 265? (a) 900 (b) 700 (c) 1100
  27. 27.Best estimate of 53 × 24? (a) 100 (b) 10000 (c) 1000
  28. 28.Best estimate of 62 × 56? (a) 360 (b) 3600 (c) 36000
  29. 29.Best estimate of 86 × 73? (a) 63000 (b) 6300 (c) 630
  30. 30.Best estimate of 26 × 29? (a) 900 (b) 9000 (c) 90
  31. 31.Best estimate of 49 × 17? (a) 1000 (b) 100 (c) 10000
  32. 32.Best estimate of 96 × 16? (a) 2000 (b) 20000 (c) 200
  33. 33.Best estimate of 793 + 371? (a) 1200 (b) 1000 (c) 1400
  34. 34.Best estimate of 29 × 81? (a) 2400 (b) 24000 (c) 240
  35. 35.Best estimate of 98 × 69? (a) 7000 (b) 700 (c) 70000
  36. 36.Best estimate of 713 + 200? (a) 900 (b) 1100 (c) 700
  37. 37.Best estimate of 89 × 21? (a) 180 (b) 1800 (c) 18000
  38. 38.Best estimate of 88 × 92? (a) 8100 (b) 810 (c) 81000
  39. 39.Best estimate of 34 × 28? (a) 90 (b) 900 (c) 9000
  40. 40.Best estimate of 251 + 609? (a) 900 (b) 1100 (c) 700

Answer key

  1. 6300
  2. 900
  3. 900
  4. 2700
  5. 1500
  6. 2500
  7. 1400
  8. 900
  9. 1000
  10. 4200
  11. 400
  12. 1000
  13. 1500
  14. 700
  15. 800
  16. 4800
  17. 3000
  18. 900
  19. 1200
  20. 2100
  21. 1200
  22. 1100
  23. 2700
  24. 7000
  25. 1200
  26. 900
  27. 1000
  28. 3600
  29. 6300
  30. 900
  31. 1000
  32. 2000
  33. 1200
  34. 2400
  35. 7000
  36. 900
  37. 1800
  38. 8100
  39. 900
  40. 900

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