186.37 .. what is this number to two sig figs

Question

theeric · Answer

Hello! So, you have a plain old decimal number.

Which digits, would you say, are most significant? When I learned this, "most significant" didn't have a meaning because it was said so much. But if you were talking about something you care about, which digits would you want to keep, because they are most considerable, or significant?

theeric · Answer

So, Money.

$123.45.

Would you like to keep this?
$123.45
    ^   ^
--------> $020.40 = $20.40

Or this?
$123.45
  ^^
--------> $120.00

I think your answer will be the latter (last one).

Now, ask yourself why.
Ask yourself, why do those digits matter most?
It should be something like, "because those digits are much more... significant... than the others." They matter MORE.

So there's you lesson in IDENTIFYING the most significant figures.

But there's a special way to represent a number, to keep only the significant figures and avoid confusion.

anonymous · Answer

thankss!!

theeric · Answer

You're welcome! Do you know how you want to rewrite it, now?

anonymous · Answer

so 190 right

theeric · Answer

I would be careful, depending on how your teacher does it. See, then someone might thing that there are $3$ significant figures there, rather than $2$. It's ambiguous. There is no standard I know of. So you go with what your teacher says.

But, definitely DON'T use a decimal! So, you're good on that point.

anonymous · Answer

how would you write it?

theeric · Answer

Well, it depends on your teacher. If I taught, I could teach that "190" is acceptable.

I might be able to guess what your teacher wants, though.

Does your teacher ask you to use something called "scientific notation" when working with significant figures?