The length of a rectangle is 12 cm and the width is 10 cm. If the width is increased by how many cm, it becomes a square.
长方形长12厘米，宽10厘米，如宽增加多少厘米就成了一个正方形．
<gadget id="calculator">12 - 10</gadget>
<output>2</output>

<result>2</result>