A business card is 6 cm long and 4 cm wide. How many square centimeters of cardboard is needed to make 25 such business cards?
一张名片，长6厘米，宽4厘米，做25张这样的名片，至少需要多少平方厘米的卡纸？
<gadget id="calculator">6 * 4 * 25</gadget>
<output>600</output>

<result>600</result>