Prepare for another incredibly fast multiplication technique! The "Ekanyunena Purvena" Sutra, which means "By One Less Than the One Before," provides a beautiful method for multiplying numbers by a series of nines (e.g., 99, 999).
When multiplying a number by a string of 9s (where both have the same number of digits), the answer comes in two simple parts:
Left Part: Is simply the original number minus 1.
Right Part: Is the complement of the original number (found using "All from 9, last from 10").
Enter a number, and we'll multiply it by the corresponding number of 9s!