Use rectangular boards with a length of 15 cm and a width of 6 cm to form a square. How many such boards should be used at least.
用长是15厘米，宽是6厘米的长方形木板拼成一个正方形，最少要用这样的木板多少块．
<gadget id="calculator">2 * 3 * 5</gadget>
<output>30</output>

<gadget id="calculator">30 / 15</gadget>
<output>2</output>

<gadget id="calculator">30 / 6</gadget>
<output>5</output>

<gadget id="calculator">2 * 5</gadget>
<output>10</output>

<result>10</result>