Answer
$1240$
Work Step by Step
$\sum ^{15}_{i=1}i^{2}=\dfrac {n\left( n+1\right) \left( 2n+1\right) }{6}=\dfrac {15\times \left( 15+1\right) \times \left( 2\times 15+1\right) }{6}=1240$
You can help us out by revising, improving and updating this answer.
Update this answerAfter you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.