X = `1` + `1/2` + `1/4` + `1/8` + .......+ `1/128` + `1/256`
X x `2` = 2 x ( `1` + `1/2` + `1/4` + `1/8` + .......+ `1/128` + `1/256` )
X x `2` = `2` + `1` + `1/2` + `1/4` + ................... + `1/128`
X x `2` = `2` + ( `1` - `1/256` )
X x `2` = 2 + `255/256`
X x `2` = `767/256`
X = `767/256` : `2`
X = `767/512`