Next to a road, a tree is planted every 5 meters from the beginning to the end, and a total of 101 trees are planted. How long is this trail?
一条道旁，从头到尾每隔5米种一棵树，共种101棵，这条小道有多长？
<gadget id="calculator">101 - 1</gadget>
<output>100</output>

<gadget id="calculator">100 * 5</gadget>
<output>500</output>

<result>500</result>