A rectangular tile with a length of 25 cm and a width of 15 cm, at least how many such tiles are needed to form a square.
一种长方形瓷砖，长25厘米，宽15厘米，至少要多少块这样的瓷砖才能拼出一个正方形．
<gadget id="calculator">75 / 25</gadget>
<output>3</output>

<gadget id="calculator">75 / 15</gadget>
<output>5</output>

<gadget id="calculator">3 * 5</gadget>
<output>15</output>

<result>15</result>