For a simple true fraction, the product of the numerator and the denominator is 252, what is the sum of all fractions that meet the conditions?
一个最简真分数，分子和分母的积是252，符合条件的所有分数的和是多少？
<gadget id="calculator">1 / 252</gadget>
<output>1/252 = around 0.003968</output>

<gadget id="calculator">4 / 63</gadget>
<output>4/63 = around 0.063492</output>

<gadget id="calculator">7 / 36</gadget>
<output>7/36 = around 0.194444</output>

<gadget id="calculator">9 / 28</gadget>
<output>9/28 = around 0.321429</output>

<gadget id="calculator">(1/252) + (4/63) + (7/36) + (9/28)</gadget>
<output>7/12 = around 0.583333</output>

<result>7/12 = around 0.583333</result>