JEE Mains · Maths · STD 11 - 6. permutation and combination
If the number of seven-digit numbers, such that the sum of their digits is even, is \(m \cdot n \cdot 10^{\mathrm{n}}\); \(m, n \in\{1,2,3, \ldots, 9\}\), then \(m+n\) is equal to _______
- A 10
- B 15
- C 14
- D 9
Answer & Solution
Correct Answer
(C) 14
Step-by-step Solution
Detailed explanation
Total 7 digit nos. \(=9000000\) 7 digit nos. having sum of digits Even \(=4500000\) \(=9.5 \cdot 10^5\) \(\mathrm{m}=9, \mathrm{n}=5\) \(\mathrm{m}+\mathrm{n}=14\)
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