If one more number is added to the known three numbers in 12, 8, and 16 so that it can form a proportional formula with the known three numbers, what is the possible number of this number?
已知三个数在12、8、16如果再添上一个数，使之能与已知三个数组成比例式，这个数可能是多少．
<gadget id="calculator">12 / 16</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">(3/4) * 8</gadget>
<output>6</output>

<result>6</result>