Question

Which of the following is not a perfect square?4 , 1, 8, 100

Answer 1

In math, it is possible to define a perfect square, the integer number that can be written as the square of another integer number.

From this definition, and because we are here working only with small numbers, we can check the first 10 integer numbers to square to check which of the given numbers is not a perfect square.

`\begin{gathered} 1^2=1 \\ 2^2=4 \\ 3^2=9 \\ 4^2=16 \\ 5^2=25 \\ 6^2=36 \\ 7^2=49 \\ 8^2=64 \\ 9^2=81 \\ 10^2=100 \end{gathered}`

From this, we can see that 1 can be written as 1², 4 can be written as 2², and 100 can be written as 10², but 8 doesn't have this integer number with a square equal to 8.

From this, we conclude that the number which is not a perfect square is 8