Nobody has ever counted to five as beautifully and harmoniously as Pentatonix has. The famous fivesome who won NBC's "The Sing-Off," will appear on Sesame Street February 7th to help teach kids about the magic of numbers. And as a special treat, a couple members of the group (namely their bass and beat boxer) who rarely get to sing out above the higher-pitched voices have their own solos.

Counting has never sounded more beautiful!