It is worth noting, in addition to the first writeup, that although
Devanagari is indeed in rows of five, for the
Katapayadi convention the rows are taken in twos, i.e.:
1 2 3 4 5 6 7 8 9 10
ka kha ga gha ~ma cha CHa ja jha ~na
ta t'ha da d'ha Na tha THa dha DHa na
pa p'ha ba bha ma
ya ra la va sha SHa sa ha LA
Knowing this, the naming of ragas such as Dhirashankarabharana makes sense: Dhi-ra, Dhi corresponds to 9 (vowel additions to consonants don't count) and ra corresponds to 2, giving us 29. Further, in order to use the Katapayadi scheme one must know the full name of the raga, as the commonly used name (Shankarabharana for Dhirashankarabharana) usually will not fit into the scheme.