The rectangle and the piece of paper are 15cm long and 12cm wide. At least how many pieces of this piece of paper are needed to form a large square.
长方形和纸片长15cm，宽12cm，至少要多少张这样的纸片才能拼成一个大正方形．
<gadget id="calculator">2 * 2 * 3 * 5</gadget>
<output>60</output>

<gadget id="calculator">60 / 15</gadget>
<output>4</output>

<gadget id="calculator">60 / 12</gadget>
<output>5</output>

<gadget id="calculator">4 * 5</gadget>
<output>20</output>

<result>20</result>