If you follow this pattern as written, you can get one scrubby using one ball of cotton. If you want a bigger scrubby, such as suggested for adult sizes, it may take more than one ball. If you want to avoid having knots in your scrubby (although I don’t think you would notice them) you can get the cone of cotton to insure that this doesn’t happen.

UPDATE:
I can’t seem to figure out how to edit my pattern so I am going to do it here: In the pattern, you need to fold down the Ch. 25 that is left and Dc, Ch 1 THROUGH BOTH of the chain spaces. in the first row around.