Uncertainty principle says that delta(x)*delta(p) >= h/(4*Pi)
p=gamma * m * v = 1/(Sqrt(1- v^2/c^2)) * m * v
where delta(x) and delta(p) are the unsertainys of position and momentum respectively, h is the planc's constant, v is the measured speed of the electron, m is the rest mass of an electron.
From there we can solve that:
delta(x) >= (h*Sqrt(1-v^2/c^2)/(4* Pi*m*delta(v)
just pit in the values and you get that delta(x) >= 1.1nm
