For each integer with more than two digits, we define its "partner number". From the following example, we can see the definition of the partner number: the number of partners for 23 is 2.3, and the number of partners for 465 is 46.5. Then start from 11 to What is the sum of all odd partners up to 999?
对于每一个两位以上的整数，我们定义一个它的"伙伴数"，从下面的例子可以看出伙伴数的定义：23的伙伴数是2.3，465的伙伴数是46.5，那么从11开始到999为止所有奇数的伙伴数的和是多少．
<gadget id="calculator">11 + 999</gadget>
<output>1_010</output>

<gadget id="calculator">999 - 11</gadget>
<output>988</output>

<gadget id="calculator">988 / 2</gadget>
<output>494</output>

<gadget id="calculator">494 + 1</gadget>
<output>495</output>

<gadget id="calculator">495 / 2</gadget>
<output>495/2 = around 247.5</output>

<gadget id="calculator">1_010 * (495/2)</gadget>
<output>249_975</output>

<gadget id="calculator">249_975 / 10</gadget>
<output>49_995/2 = around 24_997.5</output>

<result>49_995/2 = around 24_997.5</result>