Student A and student B used two screw gauges of equal pitch and...

For $A$,

Reading $= MSR + CSR + Error$

$0 . 322 = 0 . 300 + CSR + 5 \times LC$

$0 . 322 = 0 . 300 + CSR + 0 . 005$

$CSR = 0 . 017$

For $B$,

Reading $= MSR + CSR + Error$

$0 . 322 = 0 . 200 + CSR + 0 . 092$

$CSR = 0 . 030$

Difference $= 0 . 030 - 0 . 017 = 0 . 013cm$

Division on circular scale $= \dfrac{0 . 013}{0 . 001} = 13$