The most significant characteristic of smart people is in getting the ends meet even when things don’t add up. For example, if it is raining, one needs rain gear to enable dry passage. But to ensure dry passage in the absence of such a gear, you need smartness. Or say you have arranged a dinner for certain guests. If a few more land up unannounced, you need a smart person to make the same dinner suffice for all, without making it obvious.