Q12 of 140 Page 276

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

Given: first 10 letters of the English alphabet.


In 4 letter code for first position there are 10 possibilties for second position there are 9 possibilities ,for third position there are 8 possibilities and for fourth position there are 7 posiibilities since repetition is not allowed.


So total numbers of combination=10 × 9 × 8 × 7=5040


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