Grandma Wang wants to form a square vegetable field with a 15-meter fence, with one side against the wall. How big is the vegetable field?
王奶奶想把15米的篱笆围成一个正方形的菜地，一面靠墙，求菜地的占地面积有多大？
<gadget id="calculator">15 / 3</gadget>
<output>5</output>

<gadget id="calculator">5 * 5</gadget>
<output>25</output>

<result>25</result>