steel bar is sawn into a section every 4 meters. After sawing 4 times, it is just finished. How long is this steel bar in meters?
一根钢筋，每4米锯成一段，锯了4次，正好锯完，这根钢筋长多少米
<gadget id="calculator">4 + 1</gadget>
<output>5</output>

<gadget id="calculator">5 * 4</gadget>
<output>20</output>

<result>20</result>