Step-by-step explanation:
An equation that holds same number of atoms on both reactant and product side is known as a balanced chemical equation.
For example,

Here, number of reactant atoms are as follows.
C = 6
O = 13
H = 2
Number of atoms on product side are as follows.
C = 6
O = 18
H = 12
Therefore, to balance this chemical equation we multiply
on reactant side by 6.
Hence, the balanced chemical reaction equation is as follows.

Thus, we can conclude that in order to balance the equation, coefficient which must be placed in front of
is 6.