When data types are different

Hi,

I have a requirement like this:

Assignment field u2013 if it is a valid employee number then move the data to employee info object .

But the data type and length of assignment and employee are different.

Assignment: CHAR and length 18

Employee: NUMC and lenght is 8.

i am writing this routine in update rule. since data types are different i am not able to compare.

Pl suggest me is there any way to achieve this? is this possible?

Full points will be assigned!

Thanks & Regar