Saxa Loquuntur

The Greeks used various ways to indicate numbers: the most common is the alphabetic system that allocates a numeric value to individual letters of the Greek alphabet with some additional symbols:

Classical Greek inscriptions use the Attic (acrophonic) system with:

Ι = 1, 

Π = 5,               πέντε

Δ = 10,             δέκα

Η = 100,           ἑκατόν

Χ = 1000,         χίλιοι

Μ = 10000;      μύριον

and with 50, 500, 5000, and 50000 represented by composites of Π and a tiny version of the applicable power of ten· 

For an overview: (from:http://mkatz.web.wesleyan.edu/grk202/vocabulary/greek_numerals.html)

Greek numbers are avialbe via fonts like New Athenia Unicode - see the page on typing Greek.