It depends on how many shelves there are, which you did not specify. Please restate the question.
Assuming that there are just 2 shelves with 21 books on each, then the 21 books on the top shelf can be arranged in factorial 21 different ways, with the same result for the lower shelf. To find "factorial 21", which is written as 21! the calculation required is 21 x 20 x 19 x 18....and so on all the way down to ...x 3 x 2 x 1! However, with access to a scientific calculator the result for 21!can be found by first pressing the buttons for 21 followed by pressing the button labelled n!, which gives the result for 21! as 5109094217109440000 for each shelf. The result for the two shelves is 21! x 21! which is such a tremendous number that no-one could arrange books in that way if they spent their whole life at it (including from birth).
The number of different ways to arrange six books on a shelf is calculated using the factorial of the number of books. This is represented as 6!, which equals 6 × 5 × 4 × 3 × 2 × 1. Thus, there are 720 different ways to arrange six books on a shelf.
6 ways
There are 2*5! = 240 ways.
The number of ways that 15 books can be arranged on a shelf is the same as the number of permutations of 15 things taken 15 at a time. This is 15 factorial, or 15!, and is 1,307,674,368,000.
The number of ways 7 different books can be stacked on a shelf is the same as the number of permutations of 7 things taken 7 at a time, which is 7 factorial, or 5040.
You can wind up with 10 different pairs of books in your hand, which you can choose from a shelf of 5 books in 20 different ways.
The number of different ways to arrange six books on a shelf is calculated using the factorial of the number of books. This is represented as 6!, which equals 6 × 5 × 4 × 3 × 2 × 1. Thus, there are 720 different ways to arrange six books on a shelf.
792 different groups of 5 books, in 95,040 different sequences.
Stack the books on the shelf that is higher in height.
24 ways
6 ways
There are seven books on the floor. Let x be the number of books on the floor. The number of books on the shelf is 2 + 3x. From the information given, 3x + 2 = number of books on the shelf. Substitute x=7 into 3x + 2 to find the answer. So, there are 23 books on the shelf.
There are 2*5! = 240 ways.
my clossal shelf is full of books and toys
5 books can be lined up on a shelf in (5 x 4 x 3 x 2 x 1) = 120 different sequences.
120. You do 5*4*3*2*1=120. you multiply the number that you are given for example how many times can books 3 be arranged on a shelf you multiply 3*2*1=6 that is your answer
The collective noun is a shelf of books.