Simple calculation of 0.4 + 0.8 + 1.6 +. + 25.6 + 51.2

Simple calculation of 0.4 + 0.8 + 1.6 +. + 25.6 + 51.2

0.4+0.8+1.6+.+25.6+51.2
=(0.4+51.2)×128/2
=51.6×64
=3302.4