Video Poker Combiantiions

I've been reading through the Wizard's explanations for the nearly 20 trillion combinations after the draw:

"There are combin(52,5)=2,598,960 possible combinations on the deal. The reason my video poker return tables have almost 20 trillion combinations is you also have to consider what could happen on the draw. Here are the number of combinations according to how many cards the player discards.

Discards Combinations
0 1
1 47
2 1,081
3 16,215
4 178,365
5 1,533,939

The least common multiple of all those combinations is 5×combin(47,5)= 7,669,695. Regardless of how many cards the player discards, the return combinations should be weighted so that the total comes to 7,669,695. For example, if the player discards 3, there are 16,215 possible combinations on the draw, and each one of them should be weighted by 7,669,695/16,215 = 473."

I still don't get why the LCM is being used and why the combinations of each draw should be weighted. Why am I wrong in thinking that each of those 16,215 combinations of drawing 3 cards from 47 should be multiplied by combin (5,3) =10 ways of discarding 3 of 5 cards? What am I missing? Thanks.

It's because he's using integers. If you don't care about that, you can just divide the value of each combination by the number of possible combinations and use floating point numbers. e.g. if you've discarded 3 cards and draw a royal flush, that royal is worth +800/16,215 to the value of the 2-card hand. But if you only discard 1 card, the royal is relatively worth a lot more: +800/47. Using the LCM makes it possible to use integers rather than dividing and ending up with fractional values.