This method is nothing but an extension of the shortcut method explained above. When the figures of deviations appear to be big, and divisible by a common factor, this method, the figures of deviations are reduced by dividing them all by a common factor. The formulas are thus modified as under:
Where, c = Common factor by which each of the deviations is divided
d1 = the deviation from the assumed average divided by the common factor i.e., X-A/C
All other factors import the same meaning cited as before.