calculate working time in hours per month

Hello Gurus,

      I am creating a module pool program , where I am trying to calculate working time in hours per month for every employee.On screen I have provided 12 months with DAYS format.and finally calculating the number of hours in a field with QUAN having length 3 decimal 2.Now when user is providing the values in single digits its working fine but when user is providing 2 digit values its giving a dump of type p.Even I tried changing the DE of the final field like HOURS or CURR but still its giving dump.Could you please tell me about the domain which I should use for months and even for final calculation.

Thanks

Gaurav