Naughty entered a manuscript, and there are 400 words left after the entry (4/9). How many words are there in this manuscript?
淘气录入一份稿件，录入了(4/9)后还剩400字，这份稿件共有多少字？
<gadget id="calculator">4 / 9</gadget>
<output>4/9 = around 0.444444</output>

<gadget id="calculator">1 - (4/9)</gadget>
<output>5/9 = around 0.555556</output>

<gadget id="calculator">400 / (5/9)</gadget>
<output>720</output>

<result>720</result>