Because Dec 25 = Oct 31
Because OCT 31 == DEC 25
Because DEC 25 = OCT 31
The mathematician says "2" The Physicist says "2, plus or minus 0.1" The engineer says "Probably around 2, but let's say 3 to be on the safe side".
Because they got sin and cos to give them a tan.
Because OCT 31=DEC 25