.98 is the number because it was the 98th formula they created when testing for the chalk, 1.21 is the 121st formula, thats where they get the numbers from
http://www.youtube.com/watch?v=qGJxjkjtuWA&feature=share
Hd Version here:
http://www.youtube.com/watch?v=a7S7JGVBU_E&context=C4c8b9b9ADvjVQa1PpcFO-iG48L6RNtCg7Nj8eGGTrxUA4HJoO8Xo=