The total length from one end of the playground to the other end is 100 meters, and a small red flag is inserted every 4 meters from one end to the other end. Now it is necessary to insert one side every 5 meters, and how many small red flags do not need to be moved.
从运动场的一端到另一端全长100米，从一端起到另一端止每隔4米插一面小红旗．现在要改成每隔5米插一面，有多少面小红旗不用移动．
<gadget id="calculator">100 / 20</gadget>
<output>5</output>

<gadget id="calculator">5 + 1</gadget>
<output>6</output>

<result>6</result>