(1) The last number in line 8 is 64, which is the square of natural number 8, and the number in line 8 * * * is 15.

(2) The first number in the nth row is (n-1) * (n-1)+1,the last number is n*n, and the number in the nth row * * is 2n- 1.

(3)[(n- 1)*(n- 1)+ 1+n * n]*(2n- 1)/2