The combustion of the hydrogen and of the oxygen at the point of the cylinder produces solely the vapor or steam of water. Five Weeks in a Balloon by Verne, Jules View in context.
Factorial number system. In combinatorics, the factorial number system, also called factoradic, is a mixed radix numeral system adapted to numbering permutations. It is also called factorial base, although factorials do not function as base, but as place value of digits.
= n x (n-1) x (n-2) x (n-3) x ... x 2 x 1   This is the general definition of a factorial number.   If you want it in words; a factorial number is the product of all positive integers from1 to the number under consideration. 1!/1   Evaluating this statement gives   0! = 1!/1   We have just shown 1!=1 so the RHS is 1/1 or 1.  Our rearranged definition of a factorial number gives directly the statement,   0!=1 Counter intuitive perhaps but if the definition is true then this is true.