The average length of Zhang Bo's step is 5 decimeters. He walked around the playground runway for a total of 800 steps. How many meters is the length of the playground runway?
张博一步的平均长度是5分米，他绕操场跑道走了一圈共走了800步，操场跑道一圈长多少米．
<gadget id="calculator">5 / 10</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">(1/2) * 800</gadget>
<output>400</output>

<result>400</result>