Birth number and life path

The birth number adds every digit in the full date and keeps reducing the sum until one digit remains.

The same valid input always returns the same value from 1 through 9.

For entertainment, read the calculation as a compact number puzzle built from the date.

The life-path calculation also adds the full date, but it preserves 11, 22, and 33 during reduction.

This is a reproducible rule selected by BirthDB for its number facet.

For entertainment, compare this result with the one-digit birth number and notice where the arithmetic diverges.

The page places both results from the same full date side by side, making the arithmetic split at 11, 22, or 33 visible.