如;在 (1,2,3,4,5,6.........100),3的倍数有33个,3的倍数含量是100/3=33.3333...
去掉的33个3的倍数是,3,6,9,12,15,18,21,24,27,30,33,36,39,42,45,48,51,54,57,60,63,66,69,72,75,78,81,84,87,90,93,96.在这些数中,2的倍数约有33/2,5的倍数约有33/5,7的倍数约有33/7,,13的倍数约有33/13,......
也就是明处筛去3的倍数含量时,暗中也按比例筛去了2,5,7,11,13,......的倍数含量。 |