A first-grade child practices writing numbers, so he writes from 1 to 100. Among these 100 numbers, how many 1s are written in total?
一年级的小朋友练习写数，那么他从1写到100，在这100个数中，共写了多少个1．
<gadget id="calculator">1 + 11 + 8 + 1</gadget>
<output>21</output>

<result>21</result>