Take two of the six cards with 1, 2, 3, 4, 5, and 6 and write an addition formula. How many different sums are there?
从分别写着1，2，3，4，5，6的六张卡片中取两张写成一道加法算式，一共有几种不同的和？
<gadget id="calculator">1 + 1 + 2 + 2 + 1 + 2</gadget>
<output>9</output>

<result>9</result>