In order to welcome the National Day, the May 1st class will make 20 right-angled triangle small red flags. The two right-angled sides of the small red flags are 12 cm and 15 cm respectively. What is the minimum square centimeter of paper needed?
为了迎接国庆节，五一班要做20面直角三角形小红旗，小红旗的两条直角边分别是12厘米和15厘米．至少需要用纸多少平方厘米？
<gadget id="calculator">15 / 2</gadget>
<output>15/2 = around 7.5</output>

<gadget id="calculator">12 * (15/2) * 20</gadget>
<output>1_800</output>

<result>1_800</result>