First, have a calculator by your side...
or open the Calculator program in Windows and  follow the steps

1. Take the day you were born and multiply by 4
2. Add 13
3. Multiply by 25
4. Subtract 200
5. Add the month you were born
6. Multiply by 2
7. Subtract 40
8. Multiply by 50
9. Add the last 2 digits of the year you were born
10. Subtract 10500.

What do you notice ?
 

[ Birthday ] [ Profile ] [ B'day Calculator ] [ @itude number ] [ B'day Tree ]