The gymnasium bought a batch of small balls, 2 by 2, 3 by 3, and 5 by 5, all of which were just finished every time, and there was nothing left. How many balls are there at least in this batch?
体育室买来一批小皮球，2个2个、3个3个、5个5个的分每次都正好分完，没有剩余．这批皮球至少有几个？
<gadget id="calculator">2 * 3 * 5</gadget>
<output>30</output>

<result>30</result>