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I've used significant figures without really thinking about them too much; and I have never really understood there use.

I found this thread: https://www.physicsforums.com/showthread.php?t=477786&highlight=significant+figures

Where it has been argued that they should be 'taken lightly', so to speak.

Here's where I have always been confused, and I hope someone can help!:

If I were to perform the multiplication, 2.09*3.52, I have three significant figures in both numbers, and so the answer would be 7.36 (from 7.3568).

I think this example shows one issue, and that is that the 6 is not necessarily 'known'.

Indeed, depending on the numbers in the multiplication, digits in higher powers of ten columns can be affected by 'unknown' numbers in smaller powers of ten columns. So when a number is given to x significant figures, these numbers may not be the actual numbers!, since they can be influenced by unknown numbers of smaller magnitudes of ten e.g. 1/10th column, 1/100th column, etc can affect the value in the 10^{0}column or the 10^{1}column, etc.

So when I see some calculation using significant figures, I should not necessarily believe any of the numbers are absolutely certain?

I hope that makes sense!

Thanks in advance.

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# Homework Help: Understanding Sig figs

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