JEE Mains · Maths · STD 11 - 6. permutation and combination
The number of seven-digit numbers, that can be formed by using the digits \(1, 2, 3, 5\) and \(7\) such that each digit is used at least once, is :
- A \(15400\)
- B \(17800\)
- C \(16800\)
- D \(29400\)
Answer & Solution
Correct Answer
(C) \(16800\)
Step-by-step Solution
Detailed explanation
A seven-digit number is to be formed using the \(5\) digits \(1, 2, 3, 5,\) and \(7\). Since each digit must be used at least once, the remaining \(2\) places can be filled by either repeating one digit two more times, or repeating two digits one more time each. This gives rise…
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