Sumerians and Babylonians used the same cuneiform writing system with a base of 6×10, but it seems like they also used to count to 60 as 12×5… and what we’re left with, is the simplified 5+5=10.

Also, we shall remember that:

𒀭 𒐏𒋰𒁀 𒎏𒀀𒉌 𒂄𒄀 𒍑𒆗𒂵 𒈗 𒋀𒀊𒆠𒈠 𒈗𒆠𒂗 𒄀𒆠𒌵𒆤 𒂍𒀀𒉌 𒈬𒈾𒆕