For a kind of magazine, the wholesaler sells it to book stalls at 30% off the price, and the stall owner sells it to readers at a discount of 10%. If each book of this kind sells for 6.3 yuan, how much is the wholesale price of each magazine?
一种杂志，批发商按定价的七折批发给书摊，摊主将定价减少一成卖给读者，如果这种书每本卖6.3元，每本杂志的批发价是多少元？
<gadget id="calculator">10 / 100</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">1 - (1/10)</gadget>
<output>9/10 = around 0.9</output>

<gadget id="calculator">6.3 / (9/10)</gadget>
<output>7</output>

<gadget id="calculator">70 / 100</gadget>
<output>7/10 = around 0.7</output>

<gadget id="calculator">7 * (7/10)</gadget>
<output>49/10 = around 4.9</output>

<result>49/10 = around 4.9</result>