The manner in which business cards are exchanged is very revealing about a culture.

In Japan, two individuals will exchange cards, with bowing, and apologies if one side is short of business cards. This is a very individual exchange - it grows O(n2) with the number of parties meeting*.

In America, The distribution of cards tends to be more parallelized. Each participant selects as many of their cards as there are participants on the other side, and quickly slide them across the table. Asynchronously, handshakes across the table occur; the handshake process takes O(n2)*; the distribution process takes O(n). Business cards can then be left in front of participants, to use as a tool for remembering names**.

* Actually, it grows with order O(m*n), where m and n are the number of participants from each side of a meeting.
**It helps to place the cards down in the order the participants are seated.