Question

How many 3 letter code can be formed Using the first 10 letters of English alphabet, if no letter can be repeated?

Answer 1

$3$ Leter code of $10$ Letter (starting) of english

No letter repeated

$\Rightarrow (10\times 9\times 8)$

$\Rightarrow 720$ Or ${}^{10}{P}_3$

Therefore number of possible codes $=720$