 Although in the era of Hipparchus (2nd century BC) this interval was equal to the average time between lunar conjunctions, mean lunation intervals get progressively shorter due to tidal transfer of angular momentum from Earth to Moon, consequently in the present era the "molad" interval is about 3/5 of a second too long.The "molad" interval as an exact improper fraction = 29+12/24+44/1440+(10/3)/86400 = 765433/25920 days, where the denominator 25920 is the number of parts per day (each part equals 1/18 minute or 10/3 seconds) and one can alternatively write the numerator in the interesting descending sequence 765432+1.As a mixed fraction this reduces to 29+13753/25920 days, which implies an underlying fixed arithmetic lunar cycle of 25920 months in which 13753 months have 30 days and the remaining 25920 – 13753 = 12167 months have 29 days, spread as smoothly as possible.