The fuel tank of Uncle Zhang’s car has 36 liters of gasoline, and each liter of gasoline can travel 6.4 kilometers. Uncle Zhang is going to drive 144 kilometers away to do business, so how many liters of gasoline should Uncle Zhang add at least for a round trip?
张叔叔的车的油箱内有汽油36升，每升汽油可行驶6.4千米．张叔叔准备开车去144公里的外地办事，那么张叔叔往返一次至少还要加多少升汽油？
<gadget id="calculator">2 / 6.4</gadget>
<output>0.3125</output>

<gadget id="calculator">144 * 0.3125</gadget>
<output>45</output>

<gadget id="calculator">45 - 36</gadget>
<output>9</output>

<result>9</result>