Katapayadi sankhya is a simplification of Aryabhata ‘s Sanskrit numerals , due probably to Haridatta from Kerala. In Malayalam it is also known as ‘Paralperu’ For eg: ചണ്ഡാംശുചന്ദ്രാധമകുംഭിപാല represents 31415926536 which is π*1000000000000000 More examples in Malayalam are given in this page
The Katapayadi sankhya is a way of determining the number of a Melakarta raga from the first two syllables of the name of the Raga.