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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 405 · 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 13 × 72? (a) 70 (b) 7000 (c) 700
  2. 2.Best estimate of 427 + 339? (a) 500 (b) 900 (c) 700
  3. 3.Best estimate of 683 + 146? (a) 1000 (b) 800 (c) 600
  4. 4.Best estimate of 96 × 21? (a) 200 (b) 20000 (c) 2000
  5. 5.Best estimate of 380 + 678? (a) 900 (b) 1100 (c) 1300
  6. 6.Best estimate of 860 + 511? (a) 1400 (b) 1200 (c) 1600
  7. 7.Best estimate of 74 × 58? (a) 42000 (b) 420 (c) 4200
  8. 8.Best estimate of 48 × 36? (a) 2000 (b) 20000 (c) 200
  9. 9.Best estimate of 87 × 36? (a) 3600 (b) 36000 (c) 360
  10. 10.Best estimate of 642 + 482? (a) 900 (b) 1100 (c) 1300
  11. 11.Best estimate of 241 + 127? (a) 100 (b) 500 (c) 300
  12. 12.Best estimate of 88 × 47? (a) 450 (b) 4500 (c) 45000
  13. 13.Best estimate of 48 × 19? (a) 10000 (b) 100 (c) 1000
  14. 14.Best estimate of 48 × 31? (a) 1500 (b) 15000 (c) 150
  15. 15.Best estimate of 324 + 120? (a) 600 (b) 400 (c) 200
  16. 16.Best estimate of 81 × 14? (a) 8000 (b) 800 (c) 80
  17. 17.Best estimate of 728 + 410? (a) 900 (b) 1300 (c) 1100
  18. 18.Best estimate of 754 + 644? (a) 1400 (b) 1200 (c) 1600
  19. 19.Best estimate of 13 × 68? (a) 70 (b) 7000 (c) 700
  20. 20.Best estimate of 487 + 329? (a) 800 (b) 600 (c) 1000
  21. 21.Best estimate of 77 × 38? (a) 3200 (b) 320 (c) 32000
  22. 22.Best estimate of 182 + 828? (a) 1000 (b) 1200 (c) 800
  23. 23.Best estimate of 433 + 149? (a) 700 (b) 500 (c) 300
  24. 24.Best estimate of 551 + 628? (a) 1400 (b) 1200 (c) 1000
  25. 25.Best estimate of 562 + 237? (a) 600 (b) 800 (c) 1000
  26. 26.Best estimate of 66 × 58? (a) 420 (b) 42000 (c) 4200
  27. 27.Best estimate of 188 + 418? (a) 800 (b) 400 (c) 600
  28. 28.Best estimate of 370 + 179? (a) 800 (b) 600 (c) 400
  29. 29.Best estimate of 78 × 62? (a) 4800 (b) 48000 (c) 480
  30. 30.Best estimate of 40 × 18? (a) 80 (b) 8000 (c) 800
  31. 31.Best estimate of 90 × 24? (a) 1800 (b) 180 (c) 18000
  32. 32.Best estimate of 56 × 96? (a) 600 (b) 6000 (c) 60000
  33. 33.Best estimate of 54 × 37? (a) 200 (b) 2000 (c) 20000
  34. 34.Best estimate of 21 × 26? (a) 6000 (b) 600 (c) 60
  35. 35.Best estimate of 63 × 92? (a) 5400 (b) 54000 (c) 540
  36. 36.Best estimate of 31 × 61? (a) 1800 (b) 180 (c) 18000
  37. 37.Best estimate of 48 × 43? (a) 20000 (b) 2000 (c) 200
  38. 38.Best estimate of 757 + 825? (a) 1600 (b) 1800 (c) 1400
  39. 39.Best estimate of 72 × 26? (a) 21000 (b) 210 (c) 2100
  40. 40.Best estimate of 69 × 72? (a) 49000 (b) 4900 (c) 490

Answer key

  1. 700
  2. 700
  3. 800
  4. 2000
  5. 1100
  6. 1400
  7. 4200
  8. 2000
  9. 3600
  10. 1100
  11. 300
  12. 4500
  13. 1000
  14. 1500
  15. 400
  16. 800
  17. 1100
  18. 1400
  19. 700
  20. 800
  21. 3200
  22. 1000
  23. 500
  24. 1200
  25. 800
  26. 4200
  27. 600
  28. 600
  29. 4800
  30. 800
  31. 1800
  32. 6000
  33. 2000
  34. 600
  35. 5400
  36. 1800
  37. 2000
  38. 1600
  39. 2100
  40. 4900

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