Folks, ever wondered what all those confusing 4/2,  6/2 , 8/2, 10/2 etc etc sizing numbers mean for cotton yarns?
  The numbering system used is not the same for all fibers & the numbers used in relation to other fibers, do not necessarily indicate the same thing as they do for cottons.
  The 1st of the 2 numbers(or top number) indicate how many 840 yard hanks are required of a single strand of a cotton fiber to equal a pound.      Such as, a 6/2 cotton,  the number 6 means it would take 6 - 840 yard hanks to weigh a pound.
   The 2nd(or bottom) figure tells how many plys or strands of this particular weight of yarn have been twisted together.
   Thus a 6/2 cotton is composed of 2 strands of a number 6 cotton yarn that have been twisted(or spun) together.  Now you should be able to determine that a 6/2 cotton is heavier/thicker than say a 10/2 cotton.