Zhang Bing was born in 1953. In a certain year before this year, his age is a multiple of 9 and is the sum of the digits of the year. So how old is he this year?
张兵1953年出生，在今年之前的某一年，他的年龄是9的倍数并且是这一年的各位数字之和．那么这一年他多少岁．
<gadget id="calculator">17 + 1</gadget>
<output>18</output>

<result>18</result>