The sum of deviations taken from mean is

In statistics the sum of deviations of data values from mean is always zero. This is because positive deviations balance negative deviations. For example if numbers are 2 4 and 6 the mean is 4. Deviations are minus 2 0 and plus 2 which add up to zero. This property makes mean a central and balanced measure. It is the reason mean is widely used in statistical calculations.