Question

Order phenobarbital 30 mg. available: phenobarbital gr 1/4. dose to be given: _____

Answer 1

$30\,mg\times\dfrac{1\,gr}{64.79891\,mg}\times\dfrac{1\,tab}{\frac{1}{4}\,gr}=\dfrac{30\cdot 4}{64.79891}\,tab\approx1.852\,tab$

The dose to be given is about 1.85 of the 1/4 grain tablets.