Put three different numbers in the circles so that when you add the numbers at the end of each line you always get a

perfect square.

A perfect square number has four digits, none of which is zero. The digits from left to right have values that are : even, even, odd, even. Find the number.

The perimeters of two squares are 40 and 96 metres respectively. Find the perimeter of another square equal in area to the sum of the first two aquares.

A three-digit perfect square is such that if it is viewed upside down, the number seen is also a perfect square. What is the number?

[Hint: The digit 1, 0 and 8 stay the same when viewed upside down, whereas 9 becomes 6 and 6 becomes 9.]