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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 198 · 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 96 × 94? (a) 90000 (b) 9000 (c) 900
  2. 2.Best estimate of 59 × 76? (a) 48000 (b) 4800 (c) 480
  3. 3.Best estimate of 745 + 261? (a) 1000 (b) 800 (c) 1200
  4. 4.Best estimate of 30 × 62? (a) 1800 (b) 180 (c) 18000
  5. 5.Best estimate of 56 × 86? (a) 54000 (b) 540 (c) 5400
  6. 6.Best estimate of 402 + 168? (a) 600 (b) 800 (c) 400
  7. 7.Best estimate of 32 × 62? (a) 1800 (b) 18000 (c) 180
  8. 8.Best estimate of 18 × 31? (a) 6000 (b) 600 (c) 60
  9. 9.Best estimate of 716 + 386? (a) 900 (b) 1100 (c) 1300
  10. 10.Best estimate of 32 × 28? (a) 9000 (b) 900 (c) 90
  11. 11.Best estimate of 70 × 66? (a) 4900 (b) 490 (c) 49000
  12. 12.Best estimate of 602 + 642? (a) 1000 (b) 1400 (c) 1200
  13. 13.Best estimate of 97 × 67? (a) 7000 (b) 700 (c) 70000
  14. 14.Best estimate of 33 × 36? (a) 120 (b) 1200 (c) 12000
  15. 15.Best estimate of 28 × 29? (a) 90 (b) 9000 (c) 900
  16. 16.Best estimate of 67 × 16? (a) 14000 (b) 1400 (c) 140
  17. 17.Best estimate of 445 + 681? (a) 900 (b) 1300 (c) 1100
  18. 18.Best estimate of 334 + 380? (a) 900 (b) 500 (c) 700
  19. 19.Best estimate of 81 × 18? (a) 1600 (b) 160 (c) 16000
  20. 20.Best estimate of 94 × 47? (a) 4500 (b) 450 (c) 45000
  21. 21.Best estimate of 42 × 66? (a) 28000 (b) 2800 (c) 280
  22. 22.Best estimate of 30 × 47? (a) 1500 (b) 150 (c) 15000
  23. 23.Best estimate of 33 × 97? (a) 300 (b) 3000 (c) 30000
  24. 24.Best estimate of 457 + 336? (a) 600 (b) 1000 (c) 800
  25. 25.Best estimate of 784 + 283? (a) 1300 (b) 1100 (c) 900
  26. 26.Best estimate of 451 + 448? (a) 1100 (b) 700 (c) 900
  27. 27.Best estimate of 48 × 82? (a) 400 (b) 4000 (c) 40000
  28. 28.Best estimate of 768 + 243? (a) 1000 (b) 1200 (c) 800
  29. 29.Best estimate of 215 + 159? (a) 600 (b) 200 (c) 400
  30. 30.Best estimate of 81 × 87? (a) 720 (b) 72000 (c) 7200
  31. 31.Best estimate of 49 × 96? (a) 50000 (b) 5000 (c) 500
  32. 32.Best estimate of 308 + 206? (a) 700 (b) 300 (c) 500
  33. 33.Best estimate of 151 + 356? (a) 800 (b) 400 (c) 600
  34. 34.Best estimate of 33 × 33? (a) 9000 (b) 900 (c) 90
  35. 35.Best estimate of 53 × 62? (a) 300 (b) 30000 (c) 3000
  36. 36.Best estimate of 732 + 862? (a) 1400 (b) 1800 (c) 1600
  37. 37.Best estimate of 325 + 781? (a) 1100 (b) 900 (c) 1300
  38. 38.Best estimate of 39 × 41? (a) 16000 (b) 1600 (c) 160
  39. 39.Best estimate of 56 × 56? (a) 3600 (b) 36000 (c) 360
  40. 40.Best estimate of 46 × 88? (a) 45000 (b) 4500 (c) 450

Answer key

  1. 9000
  2. 4800
  3. 1000
  4. 1800
  5. 5400
  6. 600
  7. 1800
  8. 600
  9. 1100
  10. 900
  11. 4900
  12. 1200
  13. 7000
  14. 1200
  15. 900
  16. 1400
  17. 1100
  18. 700
  19. 1600
  20. 4500
  21. 2800
  22. 1500
  23. 3000
  24. 800
  25. 1100
  26. 900
  27. 4000
  28. 1000
  29. 400
  30. 7200
  31. 5000
  32. 500
  33. 600
  34. 900
  35. 3000
  36. 1600
  37. 1100
  38. 1600
  39. 3600
  40. 4500

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