I want to use Bingo with small group. What is the formula making a number of cards?

Question

I want to use colours in each blank. So 15 colours. but is there a pattern to use for each cared to ensure it's fair?

Answer 1

To avoid duplications, every card has to be different from all the others. This means you have to make combinations and select from the permutations.
So you need to choose 5 numbers from the 15(?) alotted to each column and use each one with all the others. This makes a huge number of cards possible. If you explain what you have done, so people understand why B15 never comes up, you could limit the drawing numbers to a smaller number, say B1 to B8, I16 to I24, and make your cards from that more limited set.
Or go here and print off the cards you need.
http://print-bingo.com/