The usual problem dialing phone numbers.
When younger I remembered phone numbers in a haphazard way, but when I remembered them as a string of single digits, wrote them down as single digits and then dialed them as single digits, into a phone, I sometimes got them mixed up along the way. This happened often enough that I got into the habit, when getting a wrong number, of immediately saying the number I intended to dial . That way the person I did reach could verify if I mis-dialed or had mis-wrote the number onto my note book in the first place. I am embarrassed for sending you to such a simple idea, but that is my new philosophy of the way the internet works and I am trying to conform to our new reality.
Life is made easier by simple little habits.