There are 5P3 = 5!/2! = 5*4*3 = 60 permutations.
Permutations of 10 letters taken 3 a time = 10 x 9 x 8 = 720
September has 9 letter, of which one appears 3 times. So the number of distinct permutations is 9!/3! = 120,960
because permutations are order specific, and because there are two d's "dad" counts as only one. so it is 6 (3P3)/2 (there are two d's) so the answer is 3 DAD ADD DDA
How many four-letter permutations can be formed from the letters in the word DECAGON?
There are 195 3-letter permutations.
There are 5*4*3 = 60 permutations.
4! 4 * 3 * 2 * 1 = 24
There are 5P3 = 5!/2! = 5*4*3 = 60 permutations.
The first letter of the perm can be any of the 4, the second any of the remaining 3, the third either of the remaining 2. There are thus 4 x 3 x 2 ie 24 permutations.
Permutations of 10 letters taken 3 a time = 10 x 9 x 8 = 720
4! Four factorial. 4 * 3 * 2 = 24 permutations ------------------------
How many permutations of 3 different digits are there, chosen from the ten digits 0 to 9 inclusive?
The number of permutations of the letters MASS where S needs to be the first letter is the same as the number of permutations of the letters MAS, which is 3 factorial, or 6. SMAS SMSA SAMS SASM SSMA SSAM
We know there are 10! (ten factorial) permutations (that's about 3,628,800 permutations); however, we know that number includes repeated permutations, as there are 3 s', 3 t's and 2 i's. So we have to divide by the number of ways these can be written as individual permutations (if they were considered as unique elements), which are 3! (= 6), 3! and 2! (= 2) respectively. So our final calculation would be 3628800 / (6 * 6 * 2) = 50400 unique permutations.
A - Z means you can use the whole alphabet, which usually contains 26 letters. So a one-letter code would give you 26 permutations. 2 letters will give you 26 x 26 permutations. A three letter code, finally, will give you 26 x 26 x 26 , provided you don't have any restrictions given, like avoiding codes formed from 3 similar letters and such.
There are 4*3*2*1 = 24 of them.