Many archaic cultures had words for 1, 2, 3, and “many”. You can see this tendency reflected in the Roman system where I, II, and III are obvious symbols, but IV introduces two new concepts: V for five, and the system where putting a symbol to the left represents that much less than the next symbol.
Therefore I think 1, 2, and 3 are based on counting on fingers, but 4 is where their system deviates.
Many archaic cultures had words for 1, 2, 3, and “many”. You can see this tendency reflected in the Roman system where I, II, and III are obvious symbols, but IV introduces two new concepts: V for five, and the system where putting a symbol to the left represents that much less than the next symbol.
Therefore I think 1, 2, and 3 are based on counting on fingers, but 4 is where their system deviates.