Verification number

Hi Sorry if this is considered off topic. Please ignore the post in that case. My site uses ten digit numbers as ID:s for our products. I would like the last digit to be a verification/check digit. I was just about to just make some simple function that would add the other values together into a one digit verification digit. But I thought maybe there are better or worse ways of doing this, since some algorithms probably produce a more even distribution of verification digits than others do. I.e. it would be a shame if I later on notice that half of my ID:s get 9 as verification. Any ideas? Regards Emil