It's how most of the world represents countable things. 12,345,678 things. $12,345,678 Off the top of my head, the Indian Numbering System is different: h

It's how most of the world represents countable things. 12,345,678 things. $12,345,678 Off the top of my head, the Indian Numbering System is different: https://en.wikipedia.org/wiki/Indian_numbering_system https://en.wikipedia.org/wiki/Indian_numbering_system It seems to me that the only good reason to deviate from this for non-countable things that don't have an established grouping would be any research that shows groups of 4 starting from the left is better in some way. Off the top of my head, since it's natural to pause between groups when speaking, in theory more digits-per-group = fewer groups = fewer pauses = more efficient. In any case, number grouping is something interesting to think about. It's definitely annoying to search the back of a TV and find that the serial number is 16 digits crammed together in a 2 pt. font!