To balance a chemical equation you need to know 4 steps they are
1)determine the reactants and products of chemical equation
2)now know the atoms of the reactants and products of chemical equation
3)some times there is a possibility that the coffeciantsof all the substances gettingdivided with a suitable number.since we require the lowest ratio of coefficent for reactants and products the above operation is to be done.if no common equation factor is there, there is no division of the coefficients of the substances.
4)verify the equation for the balancing of atoms on both sidesof the equation.