use jj thomson's q/m ratio thingo:
q/m = v/rB
get the values for q and m from your data sheet
–1.602 × 10–19 / 9.109 × 10–31 = 8.0 x 10-6 / r 2.1 x 10-2
-3693270392 r = 8.0 x 10-6
r = -2.166101896 x 10-3
since r is a distance it can't be a negative, so take the absolute of it
r=...