12. How many positive integers are there whose digits do not include 0 , and whose digits have sum 6 ?
```
032
Integers with digit sum 6 may be grouped according to their digits:
111111;
21111, 12111,11211, 11121,11112;
3111,1311,1131,1113;
411, 141,114;
15, 51;
6;
2211, 2121, 2112, 1221, 1212, 1122;
222;
321,312, 231, 213, 132,123;
33;
42, 24.
```
There are 32 such integers.