What made 9 + 1 to become 10?

>The best I can do is create another group and start counting from (0-9) again.

Yep, we do that too: if we have 9 and then add another 1, we get a full group. Then we write

Not in a full group yet
v
10
^
Number of groups

So let's say you keep counting above 10 until you fill up a **second** group. Then you keep on counting **five** more times. Then we call that

Not in a full group yet
v
25
^
Number of groups

>!This joke post doesn't work so well if your own username contains a number above 9!<
by
> The best I can do is create another group and start counting from (0-9) again.

Yes. Or use smaller groups. When you count all the fingers on one hand, make a sign like this in the dirt: V

When you get two V's, scratch them out and make this sign: X.

If you get four X's, XXXX and need a fifth X, then scratch them out and make a bigger group, say L.

It's very easy, just keep making bigger and bigger groups. Groups of your groups.

(I leave it as an exercise to the readers to explain to our caveman why the Roman idea of grouping your groups into bigger groups, which seems pretty intuitive to me, is inferior to positional numbering).