The product of two factors is 1620, one factor is enlarged by 4 times, and the other factor is reduced by 2 times, what is the product?
两个因数的积是1620，其中一个因数扩大4倍，另一个因数缩小2倍，那么积是多少．
<gadget id="calculator">4 / 2</gadget>
<output>2</output>

<gadget id="calculator">1_620 * 2</gadget>
<output>3_240</output>

<result>3_240</result>