Significant Digits on (SD) Problems

[nsguy1350]

The significant digit problems sometimes have answers that conflict with what I thought. I need to know what I'm doing incorrectly in order to make sure I can get those points.

When multiplying/dividing, the number of digits becomes the number of digits in the least precise number.
When taking logs, do digits = decimals, and reverse in exponentiating?
What about trig functions, that messed me up as well.
When adding/subtracting, you do to the most precise mutual digit, correct? If one had 5 decimals and the other has 2, you do 2 decimals.

Anything else?

[FabensMath]

When adding or subtracting, the answer has as many decimal places as the number with the least decimal places

4.01 + 4.003 = 8.013 actually, 8.01 for correct sig figs

When multiplying or dividing, the answer has as many sig figs as the number with the least amount of sig figs

8.02 * 3.0001 * 5.3 = 127.52... actually, 130 for correct figs (round the actual answer to two sig figs)

[nsguy1350]

But, I see strange exceptions to the rule sometimes. Take 07H-38, on the 08 Region test. How is that not 2SD?

[007math]

What are the rules for stuff that isn't exactly a number, as in time (5 mins and 36 secs or like 5 ft and 7 in)? I can never figure those out...

[nsguy1350]

I think you convert to the smallest unit, such as seconds/inches. However, I still some SDs wrong, so I'm not sure.