There is a mathematical operation symbol ⊙, which makes the following equations true: 2⊙4=8, 5⊙3=13, 9⊙7=25, then 6⊙4=how much.
有一种数学运算符号⊙，使下列等式成立：2⊙4=8，5⊙3=13，9⊙7=25，那么6⊙4=多少．
<gadget id="calculator">2 * 6</gadget>
<output>12</output>

<gadget id="calculator">12 + 4</gadget>
<output>16</output>

<result>16</result>