# How many carbon dioxide molecules are needed to make a single glucose molecule?

You need 6 molecules of ${\text{CO}}_{2}$.
Glucose is ${\text{C"_6"H"_12"O}}_{6}$.
${\text{6CO"_2 + "6H"_2"O" → "C"_6"H"_12"O"_6 + "6O}}_{2}$