4, 49, 64, and 144 are all perfect squares. Because if you think back to it 2^2 is 4, 3^2 is 9, 4^2 is 16, 5^2 is 25. 6^2 is 36, 7^2 is 49, 8^2 is 64, 9^2 is 81, 10^2 is 100. 11^2 is 121. 12^2 is 144 and so on. 12, 24, and 84 do not show up in those numbers, so they are not perfect squares.
