JEE Main2026Apr 2, Shift 2Mathematics
Q.
Let . Let be a relation on the set given by if and only if divides and . Then the number of elements in is ______.
Correct answer: 120
Solution
Count divisibility pairs with and :
: — pairs. : — pairs. : — . : — . : — .
Total divisibility pairs .
Count pairs with : for each fixed , ranges over . Summing: .
By independence, .
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