34*230+340*17
=340*23+340*17
=340*(23+17)
=340*40
=13600
99+98-97+96+95-94+.+3+2-1
=99+1+96+1+93+1+.+3+1
=(99+96+93+...+3)+33
=(99+3)*33/2+33
=1716