One whole is like all ten slices of a pizza,one tenth is a tenth of a whole so like 1 slice out of the ten slices.
8/100 is 0.08 and Carter's error is that he put the "8" in the tenths place (0.8) and the 8 in 8/100 is in the hundredths place.So 0.8 is not the same as 8/100.