The calculation method of C(n, m) is C(n, m)=n! /[m！ (n-m)！ ] = n * (n-1) * ... * (n-m+1)/[1* 2 * ... * m], such as c (5 5,2) = [5 * 4]/[/kloc-.
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In 1772, the French mathematician Vandermonde, (A.-T.) used [n]p to express the number of permutations in which p is taken from n different elements at a time.
The Swiss mathematician Euler (L.) used 177 1 and 1778 to express the number of combinations of p elements extracted from n different elements.
1830, the British mathematician peacock (g) introduced the symbol Cr to represent the number of r in a combination of n elements.
1869 or earlier, Goodwin of Cambridge used the symbol nPr to indicate the arrangement number of R elements taken out of N elements at a time, and this usage has continued to this day. According to this method, nPn is equivalent to n! .
1872, the German mathematician B.A.von introduced the symbol (np) to express the same meaning, and this kind of SignsofCombinations has been used up to now.
In 1880, Potts (R R.) indicates the number of combinations and permutations of R from n elements by nCr and nPr respectively.
In 1886, Whit-worth (A.W) uses Cnr and Pnr to represent the same meaning, and he also uses Rnr to represent the number of repeatable combinations.
1899, British mathematician and physicist Chrystal, G. used nPr and nCr to indicate the number of permutations and combinations of R non-repeating elements taken from N different elements at a time, and nHr to indicate the number of repeatable permutations in the same sense. These three symbols are still widely used today.
1904, German mathematician Neto (E.) wrote an encyclopedic dictionary, in which Arn stands for the above-mentioned nPr, Crn stands for the above-mentioned nCr, and the latter is also represented by symbol (nr). These symbols are also used in modern times.
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