A supermarket needs to make a display cabinet for aquatic products with a length of 2.2m, a width of 50cm, and a height of 1.2m. Now it is necessary to install angle irons on all sides of the display cabinet. How many meters of angle irons does this display cabinet need?
某超市要做一个长为2.2m，宽为50cm，高为1.2m的水产展示柜．现在要在展示柜各边都安上角铁，这个展示柜需要多少米的角铁？
<gadget id="calculator">50 / 100</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">2.2 + (1/2) + 1.2</gadget>
<output>3.9</output>

<gadget id="calculator">3.9 * 4</gadget>
<output>15.6</output>

<result>15.6</result>