How many small squares with an area of 1 square centimeter can be placed in a rectangle with a length of 7 cm and a width of 3 cm. (No overlapping and no gaps)
在一个长7厘米，宽3厘米的长方形里摆面积是1平方厘米的小正方形，一共可以摆多少个．(不重叠也不留空隙)
<gadget id="calculator">3 / 1</gadget>
<output>3</output>

<gadget id="calculator">7 * 3</gadget>
<output>21</output>

<result>21</result>