Dummy Credit Card Numbers

Sometimes when when you develop, for example, an online shop you need the credit card number that passes the credit card validation test.

There are many sites that could give you a bunch of random cards e.g. this one.

But much simpler to remember couple of them so you do not need to copy paste anything fromt third party resources.

There are two numbers that can be used in this situations which can be easily remembered:

4111 1111 1111 1111

and 

4242 4242 4242 4242 

I did know about the first one but I did not know about the second one which is also quite easy to remember.