# Java int addition - the long way

1. Oct 5, 2009

### NiaSphinx

Hi guys,

I'm trying to figure out a way to split up integers so I can do addition the old school way in Java.
E.g.:
1234
1234
+_____
2468

So you know start at the 4's and then add them up and move left etc.
Does anyone have any ideas on how I access the different digits of an int?

Thanks

2. Oct 5, 2009

### CompuChip

I don't know if there is some nice routine for this, but there is always the oldfashioned dirty way: to access the 10n digit (i.e. for n = 0 you get the units, for n = 1 the tens, etc) you can integer-divide by 10n and then take the result modulo 10.
For example:

1234 / 100 = 12 (as integer division produces an integer by chopping off the decimal part)
12 % 10 = 2

3. Oct 5, 2009

### NiaSphinx

Ah that does sound like a good way of doing it.
Can it work the same if the base is not 10?

4. Oct 5, 2009

### CompuChip

I suppose in base b, one can still obtain the digits at the nth position (starting from n = 0 on the right) of a number N as

$$\operatorname{digit}_n(N) = \left[ N / b^n \right] \text{ mod } b$$
where the square brackets denote the floor of the division.

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