Ordered: Lidocaine 180 mg On hand: Lidocaine 30%

1. Convert the percentage solution to mg/mL:
30\% = 30\, \text{g}/100\, \text{mL} = 300 \, \text{mg}/\text{mL}

2. Determine how many mLs are needed to obtain 180 mg of Lidocaine:
\frac{180 \, \text{mg}}{300 \, \text{mg}/\text{mL}} = 0.6 \, \text{mL}

Answer: 0.6 \, \text{mL}