Question 1203905
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Obviously, from the problem, the number of chairs is the product of two integer numbers,
greater than 1, the number of rows and the number of chairs in each row.


The only number in the list, which can not be such a product, is a prime number 19, first in the list.


<U>ANSWER</U>.  The number 19 can not the total number of chairs in the practice room.
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Solved.