A Birth Number, also called a Day Number, is calculated from just the day of the month someone was born, reduced to a single digit. It's considered a smaller, more specific influence layered on top of the Life Path Number, adding detail rather than standing as a primary reading on its own.

How to calculate it:
Take the day of the month someone was born and reduce it to a single digit, unless it's already single-digit.

Example — Birth Date: April 25, 1985
Day: 25 → 2 + 5 = 7

Birth Number: 7