Q.Sum of the binomial coefficients is :

Because $(x+y)^n$ has $n+1$ terms, the location of the middle depends on whether $n$ is even or odd: a single middle term (the $(n/2+1)$th) when $n$ is even, or two middle terms (the $((n+1)/2)$th and $((n+3)/2)$th) when $n$ is odd — both found by substituting the right value of $r$ into the general term formula. Beyond locating terms, the binomial expansion has a genuine numerical use: when $y$ is small, $(1+y)^n$ c …