Put 252 eggs in 18 boxes. The boxes are divided into two types. There are 18 large boxes and 12 small boxes. How many are there in the small boxes?
把252只蛋放在18个箱子里，箱子分两种，大箱每箱18个，小箱每箱12个，小箱有多少个．
<gadget id="calculator">18 * 18</gadget>
<output>324</output>

<gadget id="calculator">324 - 252</gadget>
<output>72</output>

<gadget id="calculator">18 - 12</gadget>
<output>6</output>

<gadget id="calculator">72 / 6</gadget>
<output>12</output>

<result>12</result>