Your Mulank is the day of the month you were born on, reduced to a single digit. Born on the 23rd, your Mulank is 2 plus 3, that is 5. The month and year play no part, which is what separates it from the Bhagyank, and each of the nine results carries a ruling planet in the table Indian Ank Jyotish uses today.
Take only the day of the month. If it is a single digit, that is your Mulank. If it is two digits, add them and, if the result is still two digits, add again. The 9th gives 9, the 23rd gives 5, and the 29th gives 11 and then 2. The day is the whole input, so everyone born on the 7th of any month in any year shares a Mulank of 7.
This is the one number in the cluster you can compute in your head, which is part of why it is so widely used. It also means the Mulank divides the population into nine groups of roughly equal size, and any reading attached to it is a statement about one ninth of everyone.
The mapping used throughout AstroZivi is 1 Sun, 2 Moon, 3 Jupiter, 4 Rahu, 5 Mercury, 6 Venus, 7 Ketu, 8 Saturn and 9 Mars. Rahu and Ketu appear here as ordinary rulers, at 4 and 7, which is a feature of the numerological table and not of the classical graha ordering.
That table is Cheiro's. It is not derived from the planetary friendships of Brihat Parashara Hora Shastra ch. 3, and where a numerology page pairs two numbers as friends or enemies, that grid disagrees with Parashara's for several planets. AstroZivi states this rather than implying a classical descent the arithmetic does not have.
Indian Ank Jyotish as practised today works with three numbers. The Mulank comes from the day alone, the Bhagyank from the full date of birth, and the Namank from the letters of your name through the Chaldean values. This tool computes the first; the linked pages compute the other two from the same inputs.
None of the three has a located classical Sanskrit source. They are living practice, and their number-to-planet assignment matches Cheiro's 1926 table, which is where this app believes it entered Indian usage. That is stated here for the same reason every other source is stated on this site: so you know exactly how far the claim can be traced.
Mulank is your birth-day number reduced to one digit - born on the 23rd gives 2 plus 3, that is 5. It uses the day of the month only, not the month or the year, and each of the nine results is assigned a ruling planet in modern Ank Jyotish.
Mulank comes from the day of birth alone; Bhagyank comes from every digit of the full date of birth. Two people born on the same day of different months share a Mulank but almost never a Bhagyank.
In the table this app uses: 1 Sun, 2 Moon, 3 Jupiter, 4 Rahu, 5 Mercury, 6 Venus, 7 Ketu, 8 Saturn, 9 Mars. It is Cheiro's mapping, and it is not the same table as the planetary friendship scheme of Brihat Parashara Hora Shastra ch. 3.
Yes. Mulank, Moolank, root number and psychic number are all names for the same figure: the day of the month of birth reduced to a single digit.
No located one. Mulank and Bhagyank are living Indian practice with no traced classical locus, and their number-to-planet assignment matches Cheiro's Book of Numbers of 1926. AstroZivi labels them as modern tradition rather than as scripture.
Pythagorean, Chaldean and Vedic numbers with the Lo Shu grid and personalized guidance.
For educational purposes. Astrological interpretations are traditional and not a substitute for professional advice.