How many fractions can be formed by taking two numbers each time from the four numbers 3, 4, 5, and 6 to form fractions.
从3、4、5、6这四个数中每次取两个数组成分数，一共可以组成多少个分数．
<gadget id="calculator">4 * 3</gadget>
<output>12</output>

<result>12</result>