There are 99 straight lines on the plane, how many points of intersection do these lines have at most?
平面上有99条直线，这些直线最多有多少个交点．
<gadget id="calculator">99 - 1</gadget>
<output>98</output>

<gadget id="calculator">99 / 2</gadget>
<output>99/2 = around 49.5</output>

<gadget id="calculator">98 * (99/2)</gadget>
<output>4_851</output>

<result>4_851</result>