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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 650 · 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 53 × 63? (a) 300 (b) 3000 (c) 30000
  2. 2.Best estimate of 458 + 582? (a) 1100 (b) 1300 (c) 900
  3. 3.Best estimate of 48 × 16? (a) 100 (b) 1000 (c) 10000
  4. 4.Best estimate of 302 + 518? (a) 800 (b) 1000 (c) 600
  5. 5.Best estimate of 865 + 684? (a) 1400 (b) 1800 (c) 1600
  6. 6.Best estimate of 77 × 49? (a) 4000 (b) 40000 (c) 400
  7. 7.Best estimate of 87 × 81? (a) 72000 (b) 7200 (c) 720
  8. 8.Best estimate of 83 × 38? (a) 3200 (b) 32000 (c) 320
  9. 9.Best estimate of 76 × 58? (a) 480 (b) 48000 (c) 4800
  10. 10.Best estimate of 541 + 726? (a) 1400 (b) 1000 (c) 1200
  11. 11.Best estimate of 337 + 282? (a) 800 (b) 600 (c) 400
  12. 12.Best estimate of 717 + 167? (a) 900 (b) 1100 (c) 700
  13. 13.Best estimate of 23 × 58? (a) 1200 (b) 120 (c) 12000
  14. 14.Best estimate of 299 + 670? (a) 1200 (b) 1000 (c) 800
  15. 15.Best estimate of 26 × 24? (a) 600 (b) 6000 (c) 60
  16. 16.Best estimate of 552 + 817? (a) 1600 (b) 1200 (c) 1400
  17. 17.Best estimate of 27 × 33? (a) 900 (b) 9000 (c) 90
  18. 18.Best estimate of 184 + 132? (a) 100 (b) 300 (c) 500
  19. 19.Best estimate of 323 + 146? (a) 200 (b) 600 (c) 400
  20. 20.Best estimate of 89 × 13? (a) 90 (b) 900 (c) 9000
  21. 21.Best estimate of 638 + 418? (a) 800 (b) 1000 (c) 1200
  22. 22.Best estimate of 225 + 878? (a) 900 (b) 1300 (c) 1100
  23. 23.Best estimate of 471 + 546? (a) 1000 (b) 800 (c) 1200
  24. 24.Best estimate of 54 × 64? (a) 300 (b) 3000 (c) 30000
  25. 25.Best estimate of 83 × 66? (a) 560 (b) 56000 (c) 5600
  26. 26.Best estimate of 57 × 39? (a) 240 (b) 24000 (c) 2400
  27. 27.Best estimate of 93 × 26? (a) 270 (b) 2700 (c) 27000
  28. 28.Best estimate of 37 × 96? (a) 4000 (b) 40000 (c) 400
  29. 29.Best estimate of 52 × 30? (a) 150 (b) 1500 (c) 15000
  30. 30.Best estimate of 165 + 736? (a) 1100 (b) 900 (c) 700
  31. 31.Best estimate of 351 + 281? (a) 900 (b) 700 (c) 500
  32. 32.Best estimate of 817 + 127? (a) 1100 (b) 900 (c) 700
  33. 33.Best estimate of 96 × 82? (a) 80000 (b) 800 (c) 8000
  34. 34.Best estimate of 30 × 29? (a) 9000 (b) 90 (c) 900
  35. 35.Best estimate of 82 × 16? (a) 16000 (b) 160 (c) 1600
  36. 36.Best estimate of 28 × 39? (a) 1200 (b) 120 (c) 12000
  37. 37.Best estimate of 84 × 20? (a) 1600 (b) 16000 (c) 160
  38. 38.Best estimate of 466 + 315? (a) 800 (b) 600 (c) 1000
  39. 39.Best estimate of 475 + 616? (a) 1300 (b) 900 (c) 1100
  40. 40.Best estimate of 369 + 263? (a) 700 (b) 900 (c) 500

Answer key

  1. 3000
  2. 1100
  3. 1000
  4. 800
  5. 1600
  6. 4000
  7. 7200
  8. 3200
  9. 4800
  10. 1200
  11. 600
  12. 900
  13. 1200
  14. 1000
  15. 600
  16. 1400
  17. 900
  18. 300
  19. 400
  20. 900
  21. 1000
  22. 1100
  23. 1000
  24. 3000
  25. 5600
  26. 2400
  27. 2700
  28. 4000
  29. 1500
  30. 900
  31. 700
  32. 900
  33. 8000
  34. 900
  35. 1600
  36. 1200
  37. 1600
  38. 800
  39. 1100
  40. 700

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