Try this trick
take out your phone and use the calculator apps.
Don't use your zip code
enter the first 3 digits of your phone number
x80 hit enter
+1 hit enter
x250 hit enter
+ the last 4 digits of your phone number then hit enter
+ the last 4 digits of your phone number again then hit enter
-250 hit enter
now divided by 2 and hit enter
I will call you later