Secret behind 4 pins for security?

Ever Wondered Why ATM PINs Have A 4-Digit Code? There’s An Interesting Reason Behind It

Operational since 1967, Automated Teller Machines (ATM) have been around for almost 50 years now and it is safe to say that they are one of the most convenient inventions ever!The machines are now installed all over the world in countless cities & towns, making it super convenient for all of us who carry around debit or credit cards. A simple swipe and you can withdraw money anywhere, anytime.
But if someone was to find or steal your card, the only barrier protecting your money is your 4-digit ATM PIN.
Ever wondered why most PINs have only 4 digits? Wouldn't it be wiser if the PIN was longer so that no one else could guess it? Isn't that why our email passwords are also expected to be 6 letters or more?
Well, Scottish inventor John Adrian Shepherd-Barron, the man who pioneered the development of the ATM machine, had also proposed a 6-digit PIN.
Before you read further, here's some trivia about the man: Barron was born in Shillong and was son to a Wimbledon ladies doubles champion, Dorothy Barron.
So, the idea of the 6-digit PIN had to be rejected because of Scot's wife Caroline. Funnily enough, the longest string of numbers that she could remember was four.
Reportedly, 6 numbers stringed together were too much information for her to recall.
Although, there are few banks that do offer 6 digit PINs for security purposes, shouldn't those of us using 4 digit PINs be thanking the woman? It gets tough to recall those 4 digits at times, imagine what 6 or more would do to us?
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