Lottery probability ! emergency !

We are given a question that states as follows for mega millions lottery

REPEAT HITS LOTTERY TIPS:

In the 5/56 (chose 5 out of 1 to 56 without repititions) MEGA Millions, on average, one lottery number will be a repeat hit from the

last drawing every other drawing or 42 percent of the time.

thats the information given.

Now the question is .. how did they calculate 42 % ? Also how true this claim is ?

I figured it has something to do with conditional probability but m not able to figure out how ? Any help will be appreciated ! project due today ! (Headbang)