Algoritm to check an int value if its valid

Hello, I want to check if an int value that is passed through a form is valid, I have used the RegularExpression control to make sure the format is correct. But I want to check the data.
It is for checking social security numbers, and in Sweden they are formed like this:
Year Month Day SecurityNumbers(X)
YYMMDDXXXX
7105250698

How do I check the values so they are correct, i.ex not older than 110 years and not younger than 18, also that the months & days are fairly correct, not more then 12 months or 30 days..

Thank you!