2022 AMC 12A Problems/Problem 16
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Problem
A \emph{triangular number} is a positive integer that can be expressed in the form , for some positive integer . The three smallest triangular numbers that are also perfect squares are , , and . What is the sum of the digits of the fourth smallest triangular number that is also a perfect square?
Solution
(Professor Chen Education Palace, www.professorchenedu.com)