Excel takes 30510 and converts it to 07/13/1983 but it should be 03/05/2010. None have a leading zero.

In all cases the last two digits are the year, the next two digits from the right are the day and the rest of the digits are the month.

More examples

11110 = 01/11/2010 (this one has only five digits)

121109 = 12/11/2009 (this one has six digits)

40909 = 04/09/2009 (this one has five digits only)

Kind Thanks,

Eddie