There is a small worm that grows very fast and can double in size every day. It can grow to 12 centimeters in 12 days, so how many days does it take for the worm to grow to 3 centimeters?
有一种小虫生长速度很快，每天可以长大一倍，它12天可以长到12厘米，那么虫子长到3厘米时用了多少天．
<result>10</result>