Long story short: you shuffle the deck. One of them picks a card. You shuffle again.
The other one picks any number. (I MEAN IT: ANY. FREAKING. NUMBER.)
And yep, you guessed it: Their card is unquestionably right there, at the exact number they selected.
Magicians call this the “Holy Grail” of card magic. And now you can do it.
It’s very, very, very good. And we can ship them to you right this minute.