Xiao Ming’s family used 85 kWh of electricity last month, and the price per kWh of electricity was 0.42 yuan. How much did Xiao Ming’s family pay for electricity last month?
小明家上个月用电85度，每度电的价格是0.42元，小明家上个月付电费多少元？
<gadget id="calculator">0.42 * 85</gadget>
<output>35.7</output>

<result>35.7</result>