The problem is a lottery problem. For the Mega Millions drawing, the official website says that there is a 1 in 306 chance of getting 3 out of the 5 regular numbers correct without matching the mega ball. The prof wants to see how we calculate this. I am stuck and getting nowhere near 306.

This is where I am at...

To figure out all the possible combinations of the 5 regular numbers is :

C(56,5) which is 3819816

from here I am lost