QJEEM21Mac938: JEE Main 2021 Mathematics - Class 11 JEEM21Mac938 Solution: Let A = {n ∈ N

B $$-$$ C $$\equiv$$ {7, 13, 19, ......, 97, .......}

Now, n² $$-$$ n $$\le$$ 100 $$\times$$ 100

$$\Rightarrow$$ n(n $$-$$ 1) $$\le$$ 100 $$\times$$ 100

$$\Rightarrow$$ A = {1, 2, ......., 100}.

So, A$$\cap$$(B $$-$$ C) = {7, 13, 19, ......., 97}

Hence, sum = $$\frac{16}{2}(7+97)=832$$