There are 100 athletes in the third grade to participate in the school long-distance running competition, and the numbers are arranged from 1 to 100. How many "1"s appear in these numbers?
三年级有100名运动员参加学校长跑比赛，号码排列是1到100．这些号码中共出现多少个"1"．
<gadget id="calculator">10 + 10 + 1</gadget>
<output>21</output>

<result>21</result>