JEE Main 2022 Mathematics question
Let S be the set of all passwords which are six to eight characters long, where each character is either an alphabet from {A, B, C, D, E} or a number from {1, 2, 3, 4, 5} with the repetition of characters allowed. If the number of passwords in S whose at least one character is a number from {1, 2, 3, 4, 5} is , then is equal to .
Answer: 7073
Solution
For a password of length n, the number with at least one numeric character is . So the total is . Here $ = ×
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