or other applications, see:
Grandi's series;
Proof that the sum of the reciprocals of the primes diverges, where one of the proofs uses a telescoping sum;
Order statistic, where a telescoping sum occurs in the derivation of a probability density function;
Lefschetz fixed-point theorem, where a telescoping sum arises in algebraic topology;
Homology theory, again in algebraic topology;
Eilenberg–Mazur swindle, where a telescoping sum of knots occurs.
Fundamental theorem of calculus, a continuous analog of telescoping series.