An analytical balance with a precision of ±0.1 mg can be converted to grams. Since there are 1000 milligrams (mg) in a gram (g), you can convert 0.1 mg to grams by dividing by 1000:
\[ 0.1 , \text{mg} = 0.1 , \text{mg} \times \frac{1 , \text{g}}{1000 , \text{mg}} = 0.0001 , \text{g} \]
Therefore, the precision of an analytical balance of ±0.1 mg is equivalent to ±0.0001 grams.