The Armenian calendar uses the Armenian numerals. The actual beginning of the Solar calendar in Armenia goes back to Navasardi 1 (August 11th), 2492 BCE, when King Haik (Orion) defeated the Babylonian King Bel (Nemruth). In order to commemorate the event in following years, he changed the first day of the year to August 11, and renamed each month of the year (less two) using his ten sons and daughters names.
The Haik calendar was based on twelve months (each month had 30 days), plus 5 days collectively called Aveliats. This combination (12x30) + 5 = 365 days in a year.
However the actual solar year on earth is 365 and one quarter day (less about 11 minutes). Over four years time, these quarter days give us one complete day. The effect of the Haik calendar was that every four years, New Years and other holidays arrived the day before, two days before every eight years, etc. until they reappeared on their original day after 1460 years. .
This 1460 cycle of time was named the "Haikia" or "Hayots" cycle of time, which was also used in Egypt. In the 552 CE council at Dvin, it was decided to use a new system for counting years, called Hayots Mets Tvakane (Armenian Great Numbers), which partially corrected the problem but it was not until 1084 that the Armenian scientist Hovhannes Sarkavag initiated a new "small year" system of counting which added one day every four years (leap days). This system ended the moving of the days on the calendar.
Dates are marked by the letters ԹՎ or the like, often with a line over, indicating "t'vin" ("in the year") followed by one to four letters of the Armenian Alphabet, each of which stands for an Armenian numeral. To translate into standard years, simply add 551 to the number. Thus, should you see an inscription reading ԹՎ ՈՀԳ, simply check the alphabet table below and see that this equals 600+70+3+551= the year 1224.
The pre-Christian Armenian Pagan calendar can be read on the Armenian pagan culture page.