1 vernier scale division VSD $=\frac{0.9}{10}=0.09 cm$

Least count $L C=1 M S D-1 V S D=0.1-0.09=0.01 cm$

Main scale reading MSR $=2.8 cm$

Number of vernier division matching main scale division $n=7$

Reading $R_1=M S R+n \times L C=2.8+7 \times 0.01=2.87 cm$

$C_2: 1$ Main scale division $MSD$ $=0.1 cm$

1 vernier scale division $V S D=\frac{1.1}{10}=0.11 cm$

Least count $L C=1 V S D-1 M S D=0.11-0.1=0.01 cm$

Main scale reading $MSR$ $=2.8 cm$

Here we should note that size of vernier scale division is bigger than main scale division, hence number of vernier division matching main scale division will be counted form back. In given figure we can see that 7th vernier scale division is matching so we shall consider $10-7=3$ rd.

Number of vernier division matching main scale division $(n)=3$

Reading $R_2=M S R+n \times L C=2.8+3 \times 0.01=2.83 cm$