There are 50 athletes in the third grade to participate in the school long-distance running competition, and the numbers are arranged from 1 to 50. How many "1"s appear in these numbers?
三年级有50名运动员参加学校长跑比赛，号码排列是1到50．这些号码中共出现多少个"1"．
<gadget id="calculator">1 / 1</gadget>
<output>1</output>

<gadget id="calculator">1 + 1 + 2 + 8 + 3</gadget>
<output>15</output>

<result>15</result>