**Here are the steps :**

- read date of birth as three numbers dd, mm, yyyy (year in 4 digits)
- count the number of days, td, from 1.1.1900 to dd.mm.yyyy (including both dates)
- For example, number of days from 1.1.1900 to 2.2.1900 is 33, (that is td=33).
- divide td by 7 and get the remainder R ( if td=33 then R=5 )