Square of 1 + square of 2 + square of 3 + square of 4 + +What is the final number of the square of 1999?

0 at the end
Because the square result is: 1, 4, 9, 16, 25, 36, 49, 64, 81, 100
121、144、169、196、225、256、289、324、361 、400………
1-9 square plus 5 at the end, 11-19 square plus 5 at the end
There are even sets of such results from 1 to 1999, so the end of the result is 0

(2 + 1) (the square of 2 + 1) (the square of 2 + 1) (the square of 2 + 1); (the square of 2 + 1)

∵（2-1）=1
∵（2+1）（2^2+1)…… (2^32+1)=(2-1)（2+1）（2^2+1)…… (2^32+1)
=(2^2-1）（2^2+1)…… (2^32+1)
……
=（2^32-1）（2^32+1）
=2^64-1

Given that the square of X part X + 1 = root 5, find x to get the value of square of square - x + square of X part X + square of X + 1

The square of X (the square of X + 1) is one of the most (x (the square of X + X + 1) x (the square of X (x + X + 1 + 1 + 1) of the (x (x) of the (x (the square of X + 1 + 1) of the (x (the square of X (x + 1 + 1) of the (x (x) of the (x (x (x + square + 1) of the (x + 1 + 1 / x) of the (x + 1 / x) of the (x + 1 / x) of the (x) of the (x (x) of the (x (x) of the (x) of the (x-square of the square of the (x (x) of the (x + x) of the square of the (x + X + X of the square of the square of the square of the square of the square of the X + X + X + X + X + X of the two of the two of the two of the two of the two of the X + 1) of the(3x & # 1

Square of 1 + square of 2 + square of 3 + square of 4 + +What is the final number of the square of 1999?