'Eighteen' in the Bible

Or those eighteen on whom the tower at Siloam fell, do you suppose they had failed in their duty more than all the rest of the people who live in Jerusalem?

where a woman was present who for eighteen years had been a confirmed invalid: she was bent double, and was unable to lift herself to her full height.

And this woman, daughter of Abraham as she is, whom Satan had bound for no less than eighteen years, was she not to be loosed from this chain because it is the Sabbath day?"