I am trying to figure out how to add [negadecimal](http://mathworld.wolfram.com/Negadecimal.html) numbers by hand.

I can add normal decimal numbers using an algorithm I learned in kindergarten: start with the least significant digits, add them, carry, move left, repeat.

```
 Carry: 1111 1
 First:  156739
Second:  948352
        =======
        1105091

```

The same algorithm, however, yields incorrect results when trying to add negadecimal numbers.

If I add these two negadecimal numbers together, this should be the result:

```
 First:  156739
Second:  948352
       ========
       19083071

```

but I am not sure what algorithm I can use to achieve this result. How can I add two negadecimal numbers?