The Attic numerals are a symbolic number notation used by the ancient Greeks. They were also known as Herodianic numerals because they were first described in a 2ndcentury manuscript by Herodian; or as acrophonic numerals (from acrophony) because the basic symbols derive from the first letters of the (ancient) Greek words that the symbols represented.
The Attic numerals were a decimal (base 10) system, like the older Egyptian and the later Etruscan, Roman, and HinduArabic systems. Namely, the number to be represented was broken down into simple multiples (1 to 9) of powers of ten  units, tens, hundred, thousands, etc.. Then these parts were written down in sequence, in order of decreasing value. As in the basic Roman system, each part was written down using a combination of two symbols, representing one and five times that power of ten.
Attic numerals were adopted possibly starting in the 7th century BCE, and were eventually replaced by the classic Greek numerals around the 3rd century BCE. They are believed to have served as model for the Etruscan number system, although the two were nearly contemporary and the symbols are not obviously related.^{[]}
The Attic numerals used the following main symbols, with the given values:
Value  Symbol  Talents  Staters  Notes  Etruscan  Roman 

1  ?  Tally mark?  ?  I  
5  ?  ?  ?  Old Greek: ?? [p?nt?] Modern:  ?  V 
10  ?  ?  ?  Old Greek: ? [deka] Modern: ?  ?  X 
50  ?  ?  ?  "?" in "?": 10 × 5 = 50  ?  L 
100  ?  ?  ?  Old Greek: ? [h?katon] Modern:  ?  C 
500  ?  ?  ?  "?" in "?": 100 × 5 = 500  ?  D 
1000  ?  ?  ?  Old Greek: ? [k?ilioi] Modern:  ?  M 
5000  ?  ?  "?" in "?": 1000 × 5 = 5000  ?  V  
10000  ?  ?  Old Greek: ? [myrion] Modern:  ?  X  
50000  ?  ?  "?" in "?": 10000 × 5 = 50000  ?  L 
The symbols representing 50, 500, 5000, and 50000 were composites of an old form of the capital letter pi (with a short right leg) and a tiny version of the applicable power of ten. For example, ? was five times one thousand.
The fractions "one half" and "one quarter" were written "?" and "?", respectively.
The symbols were slightly modified when used to encode amounts in talents (with a small capital tau, "?") or in staters (with a small capital sigma, "?"). Specific numeral symbols were used to represent one drachma ("?") and ten minas "?".
The use of "?" (capital eta) for 100 reflects the early date of this numbering system. In the Greek language of the time, the word for a hundred would be pronounced [h?katon] (with a "rough aspirated" sound /h/) and written "?", because "?" represented the sound /h/ in the Attic alphabet. In later, "classical" Greek, with the adoption of the Ionic alphabet throughout the majority of Greece, the letter eta had come to represent the long e sound while the rough aspiration was no longer marked.^{[1]}^{[2]} It was not until Aristophanes of Byzantium introduced the various accent markings during the Hellenistic period that the spiritus asper began to represent /h/, resulting in the modern Greek spelling . In modern Greek the /h/ phoneme has disappeared altogether, but the accent on the ? is retained in the standard spelling.
Multiples 1 to 9 of each power of ten were written by combining the two corresponding "1" and "5" digits, namely:
Units  ?  II  III  IIII  ?  ?I  ?II  ?III  ?IIII 
1  2  3  4  5  6  7  8  9  
Tens  ?  ?  ?  ?  
10  20  30  40  50  60  70  80  90  
Hundreds  ?  ?  ?  ?  
100  200  300  400  500  600  700  800  900  
Thousands  ?  ?  ?  ?  
1000  2000  3000  4000  5000  6000  7000  8000  9000  
Tens of thousands  ?  ?  ?  ?  
10000  20000  30000  40000  50000  60000  70000  80000  90000 
Unlike the more familiar Roman numeral system, the Attic system used only the socalled "additive" notation. Thus, the numbers 4 and 9 were written ? and , not and .
In general, the number to be represented was broken down into simple multiples (1 to 9) of powers of ten  units, tens, hundred, thousands, etc.. Then these parts would be written down in sequence, from largest to smallest value. For example:
Attic numerals are available in Unicode in the Ancient Greek Numbers block (U+10140 to U+1018F).
Numeral systems 

HinduArabic numeral system 
East Asian 
American 

Alphabetic 
Former 
Positional systems by base 
Nonstandard positional numeral systems 
List of numeral systems 