A cuboid iron sheet water tank without a cover has a length and width of 5 decimeters and a height of 4 decimeters. How many square decimeters of iron sheet should be used at least?
一个无盖长方体的铁皮水箱，长和宽都是5分米，高4分米，至少要用多少平方分米铁皮？
<gadget id="calculator">5 * 5</gadget>
<output>25</output>

<gadget id="calculator">5 * 4 * 4</gadget>
<output>80</output>

<gadget id="calculator">25 + 80</gadget>
<output>105</output>

<result>105</result>