What are the chances of this being a coincidence?

[EmmaGrundyForPM]

Years ago I got a credit card, along with a PIN, and so have had the same PIN for ages. I don't use it very often as I use my debit card for most things.

DH also has a credit card, with a different bank. He uses it a lot, more like a debit card.

We were talking this morning about the increase to £100 for contactless payments and DH was joking that I could now "borrow" his card as I wouldn't need to know the PIN, but then told me the PIN anyway - and it's the same as my card.

The number is not a "special" number, doesn't correspond to any significant date etc. Its not a number either of us would have chosen as easy to remember. It's along the lines of 8372.

DH thinks this is complete coincidence. He's adamant that this was the PIN. that came with the card. I don't think it can be, and that at some point one of us must have changed the number to be the same as the other one, although I cannot imagine why. Neither of us have ever used each others credit cards, we do have a joint bank account with debit cards and the PIN. for those isn't the same.

So is DH right, and this is just complete coincidence? I do realise that, with 4 digit PIN codes, there are a maximum.of 9999 combinations so there will be repeats. But what are the odds of the repeat being with different bank cards for a married couple?

Usually if your pin stays the same they don’t send you a note of it. So I don’t think your OH has chosen it. It’s just coincidental.

There are 15 million couples in the UK, so leaving out bigamists, polygamists and other random complications, there'd be 1500 couples in your position, OP, even if the average is only one card / PIN each. If one member of each couple, on average, has two cards, it's 3000.

All a bit skewed by people using dates of birth, so I bet there are more matching pins that if all numbers were truly random. But even if it's as low as 1500, why shouldn't you and your husband be in there?

@ThatLibraryMiss

I do realise that, with 4 digit PIN codes, there are a maximum.of 9999 combinations so there will be repeats. But what are the odds of the repeat being with different bank cards for a married couple?

If 0000 is allowed, the odds that one of you chooses a number and the other subsequently chooses the same number are 1 in 10,000. So very remote but not impossible and, given how many couples there are in the UK, it's going to happen to some of them.

It's exactly the same odds as if it were your next-door neighbour, a work colleague or a random stranger.

Chance is a funny thing.

If you have been together a number of years you may have both decided to have the same pin and completely forgotten about it.
Or it could just be a very cool coincidence.

On a similar vein, I have had a debit card for a few years which obviously has a 3 digit security code on the back

I applied for a new credit card this year and when it arrived, it has the same 3 digit security code as my debit card

Different banks, ones a visa the other is a MasterCard

Thought it was a weird coincidence!

My brother and I have thensame NI number apart from the letter at the end, his is his initial, mine is my initial. It wasn't until I worked in Payroll I realised this isn't how it is supposed to work.

Thanks everyone. Obviously just a coincidence then!