Question 1:   A student has $8$ math books, $4$ English books and $5$ history books. In how many ways can this student put the books on the shelf so that books of the same subject would stand together?

Question 2:   Five girls and five boys are sitting down on $10$ chairs one after one. In how many ways they can sit so that boys would sit on the chairs with even numbers and girls - in the chairs with odd numbers?

Question 3:   In how many ways can the orders of printing $9$ different books be distributed to $2$ factories?

Question 4:   There are $32$ students in a classroom. Each second student exchanged a pen for another one. How many times pens were exchanged?

Question 5:   How many different six-digit numbers can be formed out of $1,2,3,4,5,6,7$?  Digits should not repeat and only even digits should be at the beginning and the end of a number.