Uncle uses rectangular floor tiles with a length of 30 cm and a width of 18 cm to form a large square. How many floor tiles are needed at least?
叔叔用长30厘米、宽18厘米的长方形地砖，排成一个大正方形，最少需要多少块地砖？
<gadget id="calculator">2 * 3 * 3 * 5</gadget>
<output>90</output>

<gadget id="calculator">90 / 30</gadget>
<output>3</output>

<gadget id="calculator">90 / 18</gadget>
<output>5</output>

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

<result>15</result>