Zero to Infinity: A History of Numbers
       
      Zero to Infinity: A History of Numbers
      Walk the (Number) Line (1x9)
      
      :  01, 2007
      We have learned about natural numbers, integers, rational numbers, and irrationals. In this lecture, we'll encounter real numbers, an extended notion of number. We'll learn what distinguishes rational numbers within real numbers, and we'll also prove that the endless decimal 0.9999... exactly equals 1.