Find an 8 digit number, perfect square, the number made of its 4 last digits is one more than the number made of the 4 first digits.

Solution

Training :

Find a two digit number, perfect square, the second digit is one more than the first
(beginning easy...).

What's that, no one ? why then ?

Well, let's try a 4 digit number... still none ? are you sure ?

Well, 6 digits then ... Solution

And now the pocket calculator is hot, 10 digits... Solution

12 digits, raa sh..., my calculator displays just 10 digits ... Solution