Simple calculation 1 + 1 / 2 + 1 / 4 + 1 / 8 + 1 / 16 +... + 1 / 256 =?

Simple calculation 1 + 1 / 2 + 1 / 4 + 1 / 8 + 1 / 16 +... + 1 / 256 =?

1+1/2+1/4+1/8+1/16+...+1/256
=(1+1/2+1/4+1/8+1/16+...+1/256+1/256)-1/256
=2-1/256
=1 and 255 / 256