### Addition

Even very small children can add numbers like

##### Explanation

You can do that with ten fingers. Afterwards they learn to work with larger numbers

That is still simple. But it quickly becomes more difficult and then you go to school to really learn arithmetic, because at

you should already understand what is actually behind it. Then you learn something about the decimal system. Much later come the larger numbers, that you add together from right to left (!). Finally come decimal digits. Then it starts to be difficult.