## Elementary Technical Mathematics

$0.438~in$
We have $4$ numbered divisions on the barrel: $4 \times 0.100~in = 0.400~in$. We have $1$ small division on the barrel: $1 \times 0.025 ~in= 0.025~in$. The head reading is $13$: $13\times 0.001~in= 0.013~in$. The total measurement is: $0.438~in$.