Credit card thieves have become very good at guessing personal identification numbers.

Remembering PINs can be tough for a lot of people, which means there are a large number of very common PINs because they are easy to remember.  Cyber expert Chris Bronk says that is both bad and easy to fix, "It's unfortunate that numbers that are easy to remember are also easy to figure out."

The large database managing company DataGenetics says the top 10 most common PINs make up almost 15% of all PINs.  A recent study by DataGenetics says thieves can guess over 25% of all PINs within 20 tries.

So how safe is your PIN?  Bronk says you need to avoid certain types of numbers, "Don't pick sequential numbers, don't pick numbers that are easy to remember like 1234, or 9876.  Those are really easy to beat."

The top ten most common PINs includes numbers like 1111, 1212, 1004, and 6969.  The most common PIN is 1234 and is the PIN for over 10% of all cards in the U.S.  Bronk says the best advice is to just use the random number assigned to your card by your bank.