How to round 99.999 to four significant figures?

Question

I am really puzzled.

Answer 1

the answer is 100.0. and im positive that this is the right answer

Answer 2

100.0? i was just taught this today

Answer 3

100.0

Answer 4

I am going to guess ~ 99.9990

Answer 5

9.999x10^1

Answer 6

Wow, didnt school just start today and your already doing your homework on yahoo answers.

Your in for a long year heh!

Answer 7

Currently you have 5 significant figures (ie the number of digits that are accurate).  To remove a significant figure by rounding you are going to round up the last nine, which you then end up with 100.00.  But now you have five sig figs again, so you round off the last digit again to get...

100.0