AP EAMCET · Maths · Permutation Combination
If a seven digit number formed with distinct digits 4,6 , \(9,5,3, x\) and \(y\) is divisible by 3 , then the number of such ordered pairs \((x, y)\) is
- A 7
- B 8
- C 9
- D 10
Answer & Solution
Correct Answer
(B) 8
Step-by-step Solution
Detailed explanation
Recall that when a number is divisible by 3 then sum of its digits is also divisible by 3 . So, we have \(4+6+9+5+3+x+y=3 k\) for some \(k \in Z\) \(\Rightarrow 27+(x+y)=3 k\) So, \((x+y)\) is also some multiple of 3 . Since all the seven digit numbers is to have distinct…
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