There are two steel pipes, one is 72 centimeters long and the other is 90 centimeters long. Cut them into small pieces of the same length without wasting them. What is the longest length of each small piece in centimeters?
有两根钢管，一根长72厘米，另一根长90厘米，把它们截成同样长的小段而不浪费，每小段最长是多少厘米．
<gadget id="calculator">2 * 3 * 3</gadget>
<output>18</output>

<result>18</result>