What this number is used for
Mulank is the digit hiding in the day you were born. It is not your name, not the hour, and not the year printed on a certificate. In the tables used on LagnaLord it is treated as a temperament hint: how you tend to begin, how you recover, and which planet-label (Sun through Mars) the old lists pin to that day-digit.
Two people with the same Mulank can still live opposite lives. The number is closer to a first instinct than to a career forecast. Use it as a conversation starter with the rest of a chart, not as a rule that forbids marriage, work, or travel.