Cut a piece of rectangular white paper with a length of 12cm and a width of 20cm into a square piece of paper with the same size and the largest area possible. If there is no paper left, how many square pieces of paper can be cut at least?
把一张长12cm、宽20cm的长方形白纸裁成同样大小而面积尽可能最大的正方形纸片，纸没有剩余，至少可以裁多少个正方形纸片？
<gadget id="calculator">2 * 2</gadget>
<output>4</output>

<gadget id="calculator">20 / 4</gadget>
<output>5</output>

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

<gadget id="calculator">5 * 3</gadget>
<output>15</output>

<result>15</result>