How Long Is A Rega

The Gemara says that there is a moment each day that Hashem becomes angry at the evil doers of the world. (Berachos 7a) Rabbeinu Tam sites a Tosefta that quantifies the length of this moment, called a rega. A rega is 1/24 of an eis. An eis is 1/24 of an onah. An onah is 1/24 of a sha’ah. A sha’ah is 1/24 of the day (i.e. one hour).

 Question: What fraction of a sha’ah is a rega?

Answer: 1/24 x 1/24 x 1/24 = 1/13,824 of a sha’ah

Question: If a sha’ah is 60 minutes what fraction of a second is a rega?

Answer: Number of seconds in a hour = 60 x 60 = 3,600

Number of rega’im in an hour = 13,824

3,600 / 13,824 = 25/96 of a second