Less than 1 percent of perfect brackets left after 1st day of tournament

The first full day of the 2018 NCAA tournament is in the books, and if you are still in possession of a perfect bracket, hold onto that thing for dear life.

According to NCAA.com's bracket tracker - which follows its own March Madness bracket challenge along with those from Bleacher Report, CBS, ESPN, and Yahoo - there are thousands of perfect brackets remaining, but they don't even make up 1 percent of the total number of registered brackets.

From Thursday's slate, the two most notable upsets were Loyola Chicago's buzzer-beating triumph over Miami and Buffalo's utter decimation of Arizona.

So what the chances are that one of those select few brackets goes on to get all 63 picks right? NCAA.com notes that the odds of flipping a coin and getting heads 63 consecutive times are 1 in 9,223,372,036,854,780,000 - or roughly 9.2 quintillion.