If a rectangular brick with a length of 40 cm and a width of 30 cm is used to pave a square, how many bricks should be used at least?
用一种长40厘米、宽30厘米的长方形砖，铺成一个正方形，至少要用多少块砖？
<gadget id="calculator">2 * 2 * 2 * 3 * 5</gadget>
<output>120</output>

<gadget id="calculator">120 / 40</gadget>
<output>3</output>

<gadget id="calculator">120 / 30</gadget>
<output>4</output>

<gadget id="calculator">3 * 4</gadget>
<output>12</output>

<result>12</result>