Telescoping is the most powerful JEE summation technique. If the general term can be written as f(k)-f(k+1), the sum collapses to f(1)-f(n+1). Finding the telescoping form usually requires partial fractions for rational expressions. Common decompositions: 1/[k(k+1)]=1/k-1/(k+1), 1/[k(k+2)]=(1/2)(1/k-1/(k+2)). For the second type, the cancellation is "staggered" — the first TWO and last TWO terms survive. For triple products: 1/[k(k+1)(k+2)]=(1/2)[1/(k(k+1))-1/((k+1)(k+2))], reducing to a single-layer telescope. The key skill is recognizing WHEN a sum telescopes: look for terms that can be expressed as differences of consecutive values of some function.