The monthly electricity consumption of Chengguan No. 3 Primary School in Gulang County in the second quarter of 2015 was 309 kWh, 413 kWh, and 421 kWh. What is the average monthly electricity consumption in the second quarter?
古浪县城关第三小学2015年第二季度每月的用电量分别是309度，413度，421度．第二季度平均每月用电多少度？
<gadget id="calculator">309 + 413 + 421</gadget>
<output>1_143</output>

<gadget id="calculator">1_143 / 3</gadget>
<output>381</output>

<result>381</result>