Correct
祖率
/ zǔ lǜ /
Strokes
Example
As a Noun
Zu's ratio ［approximate ratio of the circumference of a circle to its diameter as calculated by Zu Chongzhi （祖冲之, 429-500）, i.e. between 3.1415926 and 3.1415927］
Zu's ratio ［approximate ratio of the circumference of a circle to its diameter as calculated by Zu Chongzhi （祖冲之, 429-500）, i.e. between 3.1415926 and 3.1415927］