what does this mean. 115 K C E?

Answer 1

I'd say it's an old question.

It probably stood for "115 known chemical elements". But there are 118 now: http://www.lenntech.com/periodic-chart.htm

Answer 2

You should clarify where you are getting this. If it says "115K BCE" it could mean 115,000 years Before Common Era (aka BC).

K usually denotes 1000.
K in temperature can also denote Kelvin