On a road, one pole is erected every 20m, and a total of 100 poles are erected from the beginning to the end. How long is this road?
一条路上，每隔20m架设一根电线杆，从头到尾一共架设了100根，这条路有多长？
<gadget id="calculator">100 - 1</gadget>
<output>99</output>

<gadget id="calculator">20 * 99</gadget>
<output>1_980</output>

<result>1_980</result>