At least take out how many natural numbers to ensure that there are 6 numbers divided by 9 with the same remainder.
至少取出多少个自然数，才能保证有6个数除以9的余数相同．
<gadget id="calculator">5 * 9</gadget>
<output>45</output>

<gadget id="calculator">45 + 1</gadget>
<output>46</output>

<result>46</result>