Can you solve it? A headful of PINs

According to what you read on the internet, the most popular PIN numbers are 1234, 1111, 1212 and others.

When you randomly pick the digits, what is the best strategy?

It is possible to perplex PINs.

A friend and you are talking about PINs. The digit 0 would never be used by either of you.

You say that you like to pick four random digits.

One of the digits is used twice because they like to choose three random digits.

Which strategy has the biggest pool of four-digit PINs?

I will return to the UK at 5pm with the solution. There's noSPOILERS.

Please talk about your favourite PIN numbers, passwords and randomisation strategies.

Today's puzzle was suggested by the Marriotts.

I put a puzzle here on Mondays. I like to look for puzzles. Email me if you want to suggest one.

The co-author of the children's book series Football School is me. The greatest ever quiz book is available now.

I give talks about math and puzzles to schools. Please let us know if your school is interested.