JEE Mains · Maths · STD 11 - 6. permutation and combination
The number of \(3\)-\(digit\) odd numbers, whose sum of digits is a multiple of \(7\) , is
- A \(63\)
- B \(65\)
- C \(75\)
- D \(69\)
Answer & Solution
Correct Answer
(A) \(63\)
Step-by-step Solution
Detailed explanation
Sol. \(x y z \leftarrow\) odd number \(z =1,3,5,7,9\) \(x + y + z =7,14,21\) [sum of digit multiple of 7\(]\) \(\underset{1 \text { to9 }}{x}+\underset{0 \text { to9 }}{y}=6,4,2,13,11,9,7,5,20,18,16,14,12\) \(x+y=6 \Rightarrow(1,5),(2,4),(3,3),(4,2),(5,1)\), \((6,0)\)…
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