Jens, I am passing your tests, but don't think I should be for UDF2. Take the following results:

Code:
 
number to test:HappyUDF1Result:HappyUDF2Result
0:0:0
1:1:1
2:0:0
3:0:1
4:0:0
5:0:0
6:0:0
7:1:1
8:0:0
9:0:0
10:1:1
11:0:0
12:0:1
13:1:1
14:0:0
15:0:0


3 and 12 are not happy numbers (despite my what my code says ) but still passes the tests...