A silver half-cell has E° = +0.80 V and an iron half-cell has E° = -0.44 V…

$E^\circ$ is a reduction potential, measured against the standard hydrogen electrode, which is $0.00\ \text{V}$, at $1\ \text{mol/L}$, $1\ \text{bar}$ and $298\ \text{K}$. $E^\circ_{cell} = E^\circ_{cathode} - E^\circ_{anode}$. Reversing a half-reaction changes the sign of $E^\circ$. Multiplying it changes nothing.