Question

Find the number of 4 letter words that can be formed using the letters of the word PISTON in which at

least one letter is repeated​

Answer 1

Answer:

To find the number of 4 letter words having at least one letter repeated, we find the total number of 4 letter words possible and subtract from that the number of 4 letter words having no repetition.

∴ we get the answer as = 64 - 6p4.

Step-by-step explanation:

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