YouTuber Kevin Lieber (who hosts the popular Vsauce2 series) has brought a classic math magic trick back from its ‘90s heyday. In the video, Lieber walks viewers through a magic trick where they ...

Start with a deck of cards. Before the trick, sneak a peek at the 10th card in the deck. Memorize it. Ask your volunteer to add the first and second digit of their number together. For instance, if he ...