The Conversions: 2.2, 1000, 30, 5 and 15

🧠 Why it matters

WEIGHT: 1 kg = 2.2 lb, so divide pounds by 2.2 to get kilograms (44 lb ÷ 2.2 = 20 kg). MASS: 1 g = 1,000 mg; 1 mg = 1,000 mcg; 1 grain (gr), an outdated apothecary unit that ISMP says to avoid, is approximately 60 to 65 mg, so gr 1/2 is about 30 mg. VOLUME: 1 L = 1,000 mL; 1 oz = 30 mL; 1 tsp = 5 mL; 1 tbsp = 15 mL; 1 cup = 240 mL. TEMPERATURE: °C × 1.8 + 32 = °F, and (°F − 32) ÷ 1.8 = °C, so 38.5 °C is 101.3 °F. TIME: 1 hour = 60 minutes, and exam IV questions often need minutes. Move the decimal three places for metric mass conversions: 0.25 g = 250 mg; 500 mcg = 0.5 mg. Always write a leading zero (0.5 mg) and never a trailing zero (5 mg, not 5.0 mg), and round at the end, not in the middle.

🏥 In the real world

🧒 A toddler weighs 33 lb. The order is 10 mg/kg. The nurse converts: 33 ÷ 2.2 = 15 kg, then 10 × 15 = 150 mg per dose. A student who skipped the conversion and used 33 would have given 330 mg, more than double the dose. The exam counts on that mistake.

📌 Takeaways

• Pounds to kilograms: divide by 2.2
• Metric: move the decimal three places between g, mg and mcg
• Household: 5 mL teaspoon, 15 mL tablespoon, 30 mL ounce

✅ Test yourself