A customer forgets a four-digit code of an Automatic Teller Machine (ATM) in a bank. However, he remembers that this code consists of digits 2, 3, 6 and 9. Find the largest possible number of trails necessary to obtain the correct code.

A number of four different digits is formed with the help of the digits 1,2,3,4,5,6,7 in all possible ways. How many such numbers can be formed?

The digits 1, 2, 3, 4, 5, 6, 7, 8, and 9 are written in random order to form a nine digit number.Let p be the probability that this number is divisible by 36, find 9p.

Chose the correct code {:(,"Column"-I , "Column"-II,), ((P), pK_(b) "of" X^(-) (K_(a) "of" HX = 10^(-6)), (1), 6.9), ((Q), pH of 10^(-8) M HCl, (2),8), ((R), pH of 10^(-2) "M acetic and acid solution" (Take K_(a) of acetic acid=1.6xx10^(-5)), (3), 10.7), ((S), "pOH of a solution obtained by mixing equal volumes of solution with pH 3 and 5"., (4),3.4):}