What Are The Odds ???

[ManOfValue]

I've now seen two adds by shops offering 1 million $$$ for I think 61 of 64 and another offering ½ a million $$$ for 63 of 64 in their brackets contests..
I would like to know how to calculate/what are the true odds of this happening..

[5 star bomb]

0.0000012

[ManOfValue]

OK, that sounds like its close to the answer,but how do you figure?
Whats your "formula" ?