310 repeating digits numbers

Repeating numbers carry a run of the same digit: 0888, 4444, 7777. A run is easy to catch on one hearing, so these numbers suit radio and podcast ads, the side of a van or a sign read from a moving car.

The longer the run, the rarer the number. A four-digit run at the end is the most sought after; a run of three in the middle is a good value that is still easy to say.