There are some rectangular pieces of paper with a length of 3 cm and a width of 1 cm. At least how many such pieces of paper are needed to form a square.
有一些长3厘米，宽1厘米的长方形纸片，至少需要多少张这样的纸片才能拼成一个正方形．
<gadget id="calculator">3 / 3</gadget>
<output>1</output>

<gadget id="calculator">3 / 1</gadget>
<output>3</output>

<gadget id="calculator">1 * 3</gadget>
<output>3</output>

<result>3</result>