Where does “पच्चीस” come from?
पच्चीस (Hindi) comes from Sanskrit पञ्चविंशति, from Sanskrit विंशति, from Proto-Indo-Aryan HwiHśatí, from Proto-Indo-Iranian HwiHćati, from Proto-Indo-European h₁wih₁ḱm̥t, from Proto-Indo-European dwi(h₁)dḱm̥ti — two tens; two decades; twenty; two-ten.
Ancestry of “पच्चीस”, step by step