The number of A is 18, the number of B is the number of A (4/9), the number of C is half of the number of B, what is the number of C?
甲数是18，乙数是甲数的(4/9)，丙数是乙数的一半，丙数是多少．
<gadget id="calculator">4 / 9</gadget>
<output>4/9 = around 0.444444</output>

<gadget id="calculator">(4/9) / 2</gadget>
<output>2/9 = around 0.222222</output>

<gadget id="calculator">18 * (2/9)</gadget>
<output>4</output>

<result>4</result>