How does a length of human intestines can cover more than a football field?
Heather is right. It is not so much the length of the intestines as it is the length plus the villi that increase the surface area. The villi are finger like projections that cover the surface of the intestines. If you think of the intestines as being made of terry cloth (like towels), you count the surface area of each little thread that projects, which contributes to the surface area of the entire GIT.