Pack of cards
If you are asking (or answering) a combinatorics question involving packs of cards you can make it look more elegant by using \spadesuit, \heartsuit, \diamondsuit, \clubsuit in math mode: $$\spadesuit\quad\heartsuit\quad\diamondsuit\quad\clubsuit$$ Or if you're really fussy:
\color{red}{\heartsuit} and \color{red}{\diamondsuit}
$$\color{red}{\heartsuit}\quad\color{red}{\diamondsuit}$$
You can also enter the standard Unicode characters (U+2660 BLACK SPADE SUIT etc.) literally, or copy them from here:
$$♠\quad♡\quad♢\quad♣\\ ♤\quad♥\quad♦\quad♧ $$