Yes, it's 400.
No.
No.
Yes, Any real number squared is a real number. In this case that number is 25.
Yes, it is a real number.
It is not the square of a whole number; but it is the square of a real number. If you calculate the square root of 23, you will get a real number. That real number times itself will equal 23. But the square root will not be a simple whole number. It will have an endless decimal fraction.
There are infinitely many such numbers. One such is 181.81828384881882883884...
Yes, Any real number squared is a real number. In this case that number is 25.
Any number can be multiplied by itself to create a result - in this case, 202 = 20 x 20 = 400.
not in the real world. The area of a square = The length of a side, squared. Any number squared is positive.
4/25 squared is 16/625 = 0.0256 . That's a perfectly rational number.
If x squared = 5 then x = sqrt(5) = 2.2361 (approx).
rational or real