The sum of 5 consecutive natural numbers is 90. What is the largest number among these 5 numbers?
5个连续自然数的和是90，这5个数中，最大的数是多少．
<gadget id="calculator">90 / 5</gadget>
<output>18</output>

<gadget id="calculator">18 + 2</gadget>
<output>20</output>

<result>20</result>