To make 20 triangular small flags, the bottom of the small flag is 20 cm, and the height is 15 cm. At least how many square meters of red cloth should be used?
要做20面三角形的小旗，小旗的底是20厘米，高15厘米，至少要用多少平方米的红布？
<gadget id="calculator">15 / 2</gadget>
<output>15/2 = around 7.5</output>

<gadget id="calculator">20 / 10_000</gadget>
<output>1/500 = around 0.002</output>

<gadget id="calculator">20 * (15/2) * (1/500)</gadget>
<output>3/10 = around 0.3</output>

<result>3/10 = around 0.3</result>