Question

Why do we need significant figures?

Answer 1

To accurately report the precision of a measurement we need significant figures. For example, if someone asks "what is the average speed if you drove 100 miles in 30.0 min?" you would not know how precise 100 miles is. It could be 120 miles or 90 miles, but it was just reported as 100 miles. Significant figures reduce the risk of your answer to be inaccurate.