The astronomers, physicists and mathematicians of ancient Greece were true innovators.
Ancient Greeks used letters and extra symbols to represent digits
But one thing it seems the ancient Greeks did not invent was the counting system on which many of their greatest thinkers based their pioneering
New research suggests the Greeks borrowed their system known as alphabetic numerals from the Egyptians, and did not develop it themselves as was long
I don't suppose this really matters even if it is true. It's what they did with this method that counts and they did alot of good with it.