I made a mistake while posting problem # k + 87.The problem should have read 'Prove that there exists atleast one power of 5 between 10^k and 10^k+1 where k is a Natural number.Problem # k + 88Show that the sum of any number of terms of the series1/1*2, 1/2*3, 1/3*4, 1/4*5, 1/5*6,................ is less than 1.