$9 \times 1\, {mm}=10\, {VSD}$
$\therefore 1 \,{VSD}=0.9\, {mm}$
${LC}=1\, {MSD}-1\, {VSD}=0.1 \,{mm}$
Reading $={MSR}+{VSR} \times {LC}$
$10+8 \times 0.1=10.8\, {mm}$
Actual reading $=10.8-0.4=10.4\, {mm}$
radius $=\frac{{d}}{2}=\frac{10.4}{2}=5.2 \,{mm}$
$=52 \times 10^{-2}\, {cm}$