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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 664 · 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 77 × 26? (a) 2400 (b) 240 (c) 24000
  2. 2.Best estimate of 207 + 647? (a) 1000 (b) 800 (c) 600
  3. 3.Best estimate of 272 + 876? (a) 1400 (b) 1000 (c) 1200
  4. 4.Best estimate of 723 + 590? (a) 1500 (b) 1300 (c) 1100
  5. 5.Best estimate of 32 × 30? (a) 9000 (b) 90 (c) 900
  6. 6.Best estimate of 91 × 76? (a) 720 (b) 7200 (c) 72000
  7. 7.Best estimate of 36 × 78? (a) 3200 (b) 320 (c) 32000
  8. 8.Best estimate of 68 × 49? (a) 35000 (b) 350 (c) 3500
  9. 9.Best estimate of 285 + 347? (a) 800 (b) 600 (c) 400
  10. 10.Best estimate of 12 × 61? (a) 600 (b) 60 (c) 6000
  11. 11.Best estimate of 30 × 69? (a) 2100 (b) 21000 (c) 210
  12. 12.Best estimate of 43 × 86? (a) 3600 (b) 36000 (c) 360
  13. 13.Best estimate of 54 × 18? (a) 1000 (b) 10000 (c) 100
  14. 14.Best estimate of 70 × 70? (a) 49000 (b) 490 (c) 4900
  15. 15.Best estimate of 51 × 41? (a) 200 (b) 20000 (c) 2000
  16. 16.Best estimate of 735 + 726? (a) 1200 (b) 1600 (c) 1400
  17. 17.Best estimate of 41 × 28? (a) 1200 (b) 12000 (c) 120
  18. 18.Best estimate of 718 + 288? (a) 800 (b) 1000 (c) 1200
  19. 19.Best estimate of 66 × 63? (a) 42000 (b) 4200 (c) 420
  20. 20.Best estimate of 77 × 89? (a) 720 (b) 7200 (c) 72000
  21. 21.Best estimate of 63 × 43? (a) 240 (b) 2400 (c) 24000
  22. 22.Best estimate of 600 + 848? (a) 1200 (b) 1400 (c) 1600
  23. 23.Best estimate of 399 + 458? (a) 700 (b) 900 (c) 1100
  24. 24.Best estimate of 382 + 251? (a) 900 (b) 700 (c) 500
  25. 25.Best estimate of 96 × 31? (a) 30000 (b) 3000 (c) 300
  26. 26.Best estimate of 242 + 392? (a) 800 (b) 400 (c) 600
  27. 27.Best estimate of 30 × 72? (a) 210 (b) 2100 (c) 21000
  28. 28.Best estimate of 43 × 82? (a) 32000 (b) 3200 (c) 320
  29. 29.Best estimate of 12 × 36? (a) 40 (b) 4000 (c) 400
  30. 30.Best estimate of 809 + 730? (a) 1500 (b) 1700 (c) 1300
  31. 31.Best estimate of 22 × 76? (a) 16000 (b) 160 (c) 1600
  32. 32.Best estimate of 319 + 442? (a) 900 (b) 500 (c) 700
  33. 33.Best estimate of 32 × 63? (a) 18000 (b) 180 (c) 1800
  34. 34.Best estimate of 36 × 73? (a) 28000 (b) 280 (c) 2800
  35. 35.Best estimate of 29 × 46? (a) 15000 (b) 150 (c) 1500
  36. 36.Best estimate of 29 × 54? (a) 15000 (b) 150 (c) 1500
  37. 37.Best estimate of 86 × 79? (a) 72000 (b) 720 (c) 7200
  38. 38.Best estimate of 862 + 784? (a) 1500 (b) 1700 (c) 1900
  39. 39.Best estimate of 28 × 27? (a) 90 (b) 900 (c) 9000
  40. 40.Best estimate of 51 × 60? (a) 30000 (b) 3000 (c) 300

Answer key

  1. 2400
  2. 800
  3. 1200
  4. 1300
  5. 900
  6. 7200
  7. 3200
  8. 3500
  9. 600
  10. 600
  11. 2100
  12. 3600
  13. 1000
  14. 4900
  15. 2000
  16. 1400
  17. 1200
  18. 1000
  19. 4200
  20. 7200
  21. 2400
  22. 1400
  23. 900
  24. 700
  25. 3000
  26. 600
  27. 2100
  28. 3200
  29. 400
  30. 1500
  31. 1600
  32. 700
  33. 1800
  34. 2800
  35. 1500
  36. 1500
  37. 7200
  38. 1700
  39. 900
  40. 3000

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