Card trick

Abe takes any 5 cards (at random) out of a regular 52card deck,
and gives them to Ben.

The cards happen to be the 2d 4c 5h 5d Ks.

Ben gives back the 5d to Abe.

Ben then gives his partner Cam (who could be in another room)
the 4 other cards, in this order: 2d 5h 4c Ks.

Cam looks at the cards and tells Abe: you got the 5 of diamonds!

Of course, Ben sent Cam a signal; what is the signal?

NOTE: there is no "tricks" like upside down cards...

By giving him the 2D first this tells him it is a diamond and the 2 corresponds to place where the number is. So we have 5D.

Worth a try

No, not quite.
But "2D first indicates the suit" is correct.

Hint: the "arrangement" of the 3 other cards is important.

It's real neat; I played it a few times with my daughter as
partner at family Xmas parties...think Curly will remember.

That's all I have, maybe someone else can figure out the 2nd part.

The 5 is out of order, indicating the card is a five.

No, that is accidental to these cards.
The 5 cards I used is just one example.

Hint: last 3 cards are arranged to represent
the number of the retained card.

I was thinking that, but I couldn't figure out how that would work. 5+4=9 but what does the K add up to a 10 or 13, either way
subtract 9 from it, that doesn't work. subtract 4 from 5 then subtract 1 from K, that doesn't work. None of my math ponderings work unless it's algebraic and that's out of my league.

Clue: arrange numbers 1 to 13 in a circular form (like a 13-hour clock).
Notice (as example) that clockwise 1 is 7 away from 8
but counterclockwise 1 is 6 away from 8.

ANUTter hint:

From this:
"The cards happen to be the 2d 4c 5h 5d Ks.
Ben gives back the 5d to Abe.
Ben then gives his partner Cam (who could be in another room)
the 4 other cards, in this order: 2d 5h 4c Ks."

Why order 5h 4c Ks?

5h 4c Ks = 5 4 13 = 2 1 3 = 3***
This result is added to 1st card 2d: 3 + 2 = 5; so 5d

*** There are 6 possible arrangements:
1 2 3 = 1
1 3 2 = 2
2 1 3 = 3
2 3 1 = 4
3 1 2 = 5
3 2 1 = 6

If I have this right.....

So it looks like by drawing 5 cards you'll always have two cards with a like suit which you use intially to name the suit. Then, the cards are ordered in one of the six ways you've outlined. Your partner has memorized these orders along with the appropriate values. The arrangemnt of the cards must be done in some fashion to identify if the direction should be CW or CCW possibly with the center card above or below the other two cards. My only question would be if you have two cards with the same value remaining, how do you identify the order? Is there a specific order for the suit reference?

Example: 3c 9h 9d 10c Js

Yagotit Cue!
The "suit values" are 1st agreed upon;
like h > d > c > s

This is the way I "try" to explain it:
.............................................................
Detailed solution:
-arrange numbers 1 to 13 in a circular form (like a 13 hour clock);
you'll see that the maximun distance between any 2 numbers is 6

-with 5 cards, you're sure to have at least 2 of same suit

-let's suppose the card are 3d 5c 7s Jh Qc; you would give back
the 5c; now you have to signal this to your partner

-you pass the cards in this order: Qc Jh 7s 3d

-the 1st one indicates the suit; also its "value" (12) acts as a "peg"

-you want to send signal "6"; the "5" is 6 away from "12" (13-1-2-3-4-5)

-there are 6 possible arrangements of these 3 cards:
123(1) 132(2) 213(3) 231(4) 312(5) 321(6)

-passing in order Jh 7s 3d represents 321, or signal 6

If the 3 "signal cards" happen to be same "value", go by suit strength.

Also, the "suit signal card" can be in another position; does not need
to be the 1st card; you work that out with your partner; good idea to
change position now and then: less apparent to "spectators" !
...............................................................

By the way, it's sure a neat trick to pull at a party.
I practiced it with my daughter as partner: sure lotta fun.