The problem of mathematical simple calculation 1/2+1/4+1/8+1/16+1/32+1/64+1/128+1/256

The problem of mathematical simple calculation 1/2+1/4+1/8+1/16+1/32+1/64+1/128+1/256

=128/256+64/256+32/256+16/256+8/256+4/256+2/256+1/256
=255/256