How do mortgage brokers come up with your one credit score?

I know my three credit scores. But how do mortgage brokers come up with the one score? The only thing that I have heard is that they average out the three. That doesn't seem right. Need to know.How do mortgage brokers come up with your one credit score?
They throw out the high and low and use the one in the middle!How do mortgage brokers come up with your one credit score?
There are three credit reporting company's. The mortgage brokers get it from them. if you want to know who these credit reporting company's are why don't you ask your banker,thy should be able to tell you. hope that helps some.
Your credit scores between all the reporting agencies cannot vary to any great degree, so averaging is proper.
From past experience, they use the middle one.