How many square decimeters of boards are needed to make a cubic wooden box without a cover with a side length of 7 decimeters?
做一个棱长7分米的无盖正方体木箱，至少需要木板多少平方分米？
<gadget id="calculator">7 * 7 * 5</gadget>
<output>245</output>

<result>245</result>