How to calculate valence factor (n-factor) for a element? Suppose I am given some reaction in which 
$$\ce{C6H12O6 -&gt; CO2}$$
and I want to calculate n-factor for this reaction to ultimately calculate equivalent weight of carbon for this reaction. Since $$E=\frac{M}{n}$$
I know that n-factor is no of electron gained/lost by one atom of a compound.

So Initial Oxidation state of carbon is $$6x + 12-12=0$$ $$x=0$$ meaning 
and final oxidation state of carbon is $$-4$$ Hence, n-factor of this reaction should be $4$ but it's given to be $28$. How is this possible? Can someone explain how to correctly calculate n-factor with few more examples?
Hint :  

n-factor of a molecule/compound is defined as the change in oxidation state per molecule.
You have correctly calculated the change of one carbon atom as 4.
But how many carbon atoms are there in the glucose molecule?  

Note:  


The average oxidation state of carbon in glucose is zero while in reality the different carbons have different OS. (Reference)  
n-factor of a reaction is not defined but it is defined for a single species participating in that reaction.   
n-factor of glucose is not equal to the n-factor of the product formed in that reaction, that is, $\ce{CO_2}$.