A small triangular flag with a base of 12 cm and a height of 15 cm. How many square centimeters of paper do you need to make 40 small flags like this?
一种三角形小旗，底12厘米，高15厘米．做40面这样的小旗，至少需要多少平方厘米的纸？
<gadget id="calculator">15 / 2</gadget>
<output>15/2 = around 7.5</output>

<gadget id="calculator">12 * (15/2) * 40</gadget>
<output>3_600</output>

<result>3_600</result>