Numbers like 1, 4, 9, 16, 25, ... are known as ________.
Perfect squares
When an integer is multiplied by itself, it results in a perfect square.
When we square integers like 1, 2, 3, 4, 5, ..., we obtain 1, 4, 9, 16, 25, ... .
Hence, the given numbers which are obtained by squaring the integers are known as perfect squares.