Comments by "Jovet" (@jovetj) on "Numberphile" channel.

  1. I prefer Professor Definitely I. Doublestruck.
    4
  2. 18:30 Those letters are more-properly called doublestruck. As in, if you were on a manual typewriter, you would type the letter, backspace, and type it again. (Most of the time, the first and second would not be in exactly the same horizontal position because the backspace isn't that precise.)
    1