How the magic numbers for months (622503514624) to calculate day of the week for a given date, is calculated?

Answer 1

Basant, don't know if this helps, but maybe it is related:

http://ludism.org/mentat/CalendarFeat

Answer 2

Please delete the other post.

Answer 3

Seemed that you post this question twice?

Answer 4

Sorry, network issue! Now fixed.