You can manually calculate the day of the week on which you were born simply by following a formula. First, divide the last two digits of the year by four. Then, add the integer part of this to the last two digits of your year of birth. Now add the a number to this which is date of your birth month. You then need to add a number corresponding to your birth month and birth century, by referencing the website mentioned in my post. The you divide all of this by seven, and the remainder is a code for the day of the week, with 1 being Sunday, 2 being Monday and so on, with zero corresponding to Saturday. This website also has a couple of examples for you to reference: