Four consecutive natural numbers, which are multiples of 3, multiples of 5, multiples of 7, and multiples of 9 in ascending order, what is the minimum sum of these four consecutive natural numbers?
四个连续的自然数，它们从小到大顺次是3的倍数、5的倍数、7的倍数、9的倍数，这四个连续的自然数的和最小是几？
<gadget id="calculator">18 * 9</gadget>
<output>162</output>

<gadget id="calculator">159 + 160 + 161 + 162</gadget>
<output>642</output>

<result>642</result>