he chemical formula for a carbohydrate is C6 H12 O6
you have your 6 carbons (the carbo-) and you have 6 water molules (-hydrate). H12O6 means that for every one oxygen there is two hydrogens, which is the set up of a water molecule.
C+C+C+C+C+C+H2O+H2O+H2O+H2O+H2O+H2O
=C6 H12 O6