Significant Figures addition & conversion

[physicsteach]

Having a discussion with a colleague over sig figs and conversions.

Original problem: find perimeter of 12.6 ft by 13.88 ft room and express answer in meters.

16.1 m or 16.2 m?

Question is when to round? After finding perimeter in feet? 53.0 feet to meters = 16.2 meters or at the end? 52.96 feet = 16.1 meters?

 

[daveb]

I find it's usually best to round at the final answer.

 

[SammyS]

I find it's usually best to round at the final answer.

(Emphatically) agree !

 

[Johnson]

Keep as many digits throughout your work as you can, then round at the end.