[joshuaheard]

This is why phone numbers are 7 digits long: xxx-xxxx. Then, add another "chunk" for the area code: (xxx) xxx-xxxx.

[isostatic]

Phone numbers are 11 digits long, usually split into 5 and 6, but sometimes 4/7 or 3/8, and even 6/5 and 7/4.

Not that anyone remembers phone numbers nowadays.

[aidenn0]

It was even shorter before when the exchange was represented with a word and a number (e.g. KLondike 5 for 555).