The clock strikes 1 at 1 o'clock, 2 at 2 o'clock, 3 at 3 o'clock, and so on, how many times from 1 o'clock to 12 o'clock in total.
时钟1点敲1下，2点敲2下，3点敲3下，依此类推，从1点至12点一共敲多少下．
<gadget id="calculator">1 + 12</gadget>
<output>13</output>

<gadget id="calculator">12 / 2</gadget>
<output>6</output>

<gadget id="calculator">13 * 6</gadget>
<output>78</output>

<result>78</result>