Popsugar Celebrity Celebrity Instagrams John Legend Celebrates 42nd Birthday With Math Competition Chrissy Teigen Went All Out For John Legend's Birthday Math-Off — See the Pics! December 29, 2020 by Yerin Kim First Published: December 28, 2020 View On One Page Photo 6 of 7 ADVERTISEMENT () Start Slideshow Share This Link Copy ← Use Arrow Keys → 6 Previous Next Start Slideshow John LegendCelebrity InstagramsChrissy TeigenCelebrity BirthdaysCelebrity FriendshipsJen Atkin