A number is decreased by 25% and then increased by 25%. The number so obtained is 8 less than the original number. What was the original number?

128

             Actual No.   :    New No.      

-25%             4        :       3

+25%            4        :       5

Total Effect   16      :     15    ⇒    1 (decrease)

         1 Unit = 8

    Original no. is = 16 Units = 16 × 8 = 128