IMAS 2021 — Middle Primary Grades 3–4 — Round 1 Question 8

A certain year in the 21st Century is a perfect square number. What year is it? (Note: $ 1=1^{2} $, $ 4=2^{2} $, $ 9=3^{2} $, ..., so we call 1, 4, 9, ... perfect square numbers.)