To express a compound mass as a decimal in kilograms, convert the gram part to kilograms by dividing by 1000, then add.<br><br>
&bull; 300 g = 300 ÷ 1000 = 0.3 kg<br>
&bull; 2 kg + 0.3 kg = 2.3 kg<br><br>
Final Answer: 2.3 kg