Question

How many 4-letter code can be formed using the first 10 letters of the English alphabet, if no letter can be repeated?

Answer 1

Without repeating, number of 4 letter coeds from first 10 alphabets

= 10P4
= 10! / (10-4)!
= 10*9*8*7
=5040

Answer 2

$\textbf{Answer is in Attachment !}$

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