{{Greek numeral|666}} returns ΧΞϚ´

For numbers greater than 9,999 the myriad notation is in use, e.g. {{Greek numeral|10000}} returns

A comma (, - historically the lower keraia symbol ͵ ) before a letter denotes a thousandth (arithmetic value of the letter * 1000).

The acute accent (´ - historically the upper keraia symbol ʹ ) at the end of the number denotes a number (historically this also used to be an overline).

The M symbol (myriad) stands as a multiplier of 10.000 for each of the letters on top of it.