Helek

The helek, also spelled chelek (Hebrew חלק, meaning "portion", plural "halakim" חלקים) is a unit of time used in the calculation of the Molad. Other spellings used are "chelak" and "chelek", both with plural "chalakim".
The hour is divided into 1080 halakim. A helek is 3 seconds or 1/18 minute. The "helek" derives from a small Babylonian time period called a "she", meaning '"barleycorn", itself equal to 1/72 of a Babylonian time degree (1° of celestial rotation).
The Hebrew calendar defines its mean month to be exactly equal to 29 days 12 hours and 793 halakim, which is 29 days 12 hours 44 minutes and 3 seconds. It defines its mean year as exactly 235/19 times this amount, or 365.2468222 days.