Chemistry Significant figures help?! please?

[luckycharm]

I just cannot get the significant figures right. I missed it on the test. I have two problems:

1. 6.167+83 / 5.10
My answer was 17.5 rounded = 18... she counted it wrong... what should it have been?

possible answers are a. 17.48 b. 20 c. 18 X wrong d. 17.5 e. 17

question #2. Using the rules of significant figures, calculate the following: 4.0021 - .004
possible answer are a) 4.00 b)3.9981 c)4.0 and d)3.998


any help would be appreciated.

[Nurse betty]

E. 17

my calc showed 17.48
and you only need 2 sig figs, so you would be looking at 17.4. so the answer would be 17.