If (31/90)＜(90/(()))＜(12/31) holds true, how many natural numbers can be filled in □?
如果(31/90)＜(90/(()))＜(12/31)成立，则□中可填的自然数共有多少个．
<gadget id="calculator">261 - 233</gadget>
<output>28</output>

<result>28</result>