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

Question

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## Answers ( )

Answer:Hence, 5040 four-letter codes can be formed using the first 10 letters of the English alphabet, if no letter is repeated.

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

➡️Let the 4 digit code be 1234.➡️At the first place, the number of letters possible is 10.➡️Let’s suppose any 1 of the ten occupies place 1.➡️Now, as the repetition is not allowed, the number of letters possible at place 2 is 9.➡️Now at 1 and 2, any 2 of the 10 alphabets have been taken.➡️The number of alphabets left for place 3 is 8 and similarly the number of alphabets possible at 4 is 7.➡️Therefore the total number of 4 letter codes=10 × 9 × 8 × 7=5040.━━━━━━━━━━━━━━━━━━━━━━━━━