JEE Mains · Maths · STD 11 - 6. permutation and combination
Let m and \(\mathrm{n},(\mathrm{m} \lt \mathrm{n})\) be two 2-digit numbers. Then the total numbers of pairs \((m, n)\), such that \(\operatorname{gcd}(m, n)=6\), is ________
- A 60
- B 64
- C 72
- D 84
Answer & Solution
Correct Answer
(B) 64
Step-by-step Solution
Detailed explanation
Let \(\mathrm{m}=6 \mathrm{a}, \mathrm{n}=6 \mathrm{~b}\) \(\mathrm{m} \lt \mathrm{n} \Rightarrow \mathrm{a} \lt \mathrm{b}\) where \(\mathrm{a} \& \mathrm{~b}\) are co-prime numbers also since \(m \& n\) are 2 digit nos, so…
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