Crazy, Man

I know there is a mathematical equation hidden somewhere in here (and I'm also sure that if the husband saw it, he would love to explain it in detail to me - at midnight, of course,) but this is pretty neat for us right-brained folks!

MATH TRICK

1. GRAB A CALCULATOR. (YOU WON'T BE ABLE TO DO THIS ONE IN YOUR HEAD)
2. KEY IN THE FIRST THREE DIGITS OF YOUR PHONE NUMBER (NOT THE AREA CODE)
3. MULTIPLY BY 80
4. ADD 1
5. MULTIPLY BY 250
6. ADD THE LAST 4 DIGITS OF YOUR PHONE NUMBER
7. ADD THE LAST 4 DIGITS OF YOUR PHONE NUMBER AGAIN
8. SUBTRACT 250
9. DIVIDE NUMBER BY 2

DO YOU RECOGNIZE THE ANSWER?