Cell Potential Calculator
Battery voltage from the two half-reaction potentials.
Reading the table right
E°cell = E°cathode - E°anode
Both values come off the standard reduction potential table; you subtract the anode's as-listed value rather than flipping its sign yourself. Copper (+0.34) against zinc (-0.76) gives 1.10 V: the Daniell cell, the battery that ran the telegraph age.