College Algebra, Chapter 9, Review Exercises, Section Review Exercises, Problem 46

Write the sum of $1^2 + 2^2 + 3^2 + ... + 100^2$ using sigma notation. Do not evaluate.
A natural way to write this sum is
$\displaystyle 1^2 + 2^2 + 3^2 + ... + 100^2 = \sum^{100}_{k = 1} k^2$