Why is it necessary to have six co2 entering the chloroplast?

One of the main functions of the chloroplast is its role in photosynthesis, the process by which light is transformed into chemical energy, to subsequently produce food in the form of sugars. Water (H 2 O) and carbon dioxide (CO 2) are used in photosynthesis, and sugar and oxygen (O 2) is made, using light energy.

so it necessary to have six co2 entering the chloroplast to make 6 carbon glucose