Put a red flag on the side of a road. Insert one side every 5 meters, and do not insert at both ends. A total of 100 red flags are needed. How many meters is the total length of this road?
在一条公路的一侧插红旗．每隔5米插一面，且两端都不插，一共需要红旗100面，这条路全长多少米？
<gadget id="calculator">100 + 1</gadget>
<output>101</output>

<gadget id="calculator">101 * 5</gadget>
<output>505</output>

<result>505</result>