DEV Community

Discussion on: Daily Challenge #163 - Significant Figures

Collapse
 
idanarye profile image
Idan Arye

Trailing zeroes in a number with a decimal point are significant
78.200 has 5 significant figures
20.0 has 3 significant figures

Trailing zeroes in a number without a decimal point are not significant
1200 has 2 significant figures
345000 has 3 significant figures

Shouldn't it be the other way around?

Collapse
 
savagepixie profile image
SavagePixie

Yes, but I suppose it's changed to avoid the obvious string -> number -> string conversion that would take care of non-significant zeros.

Collapse
 
schwepmo profile image
schwepmo

Well actually, no. See my response :D

Thread Thread
 
idanarye profile image
Idan Arye

Still doesn't explain why "Trailing zeroes in a number without a decimal point" are not significant, considering how each such zero increases the number by an order of magnitude and how appending .0 suddenly makes these zeroes significant.

Thread Thread
 
schwepmo profile image
schwepmo

Check the Wikipedia article it explains that aswell. Short answer is, that trailing zeros are somewhat ambiguous and that you have to specify it by some rule, which is done by the task description.

Collapse
 
schwepmo profile image
schwepmo

I just checked on Wikipedia and it is right the way that it is stated in the task. This is because if you add zeros after the decimal point, you imply that your number was "measured" with a higher precision.

Example: a normal ruler vs. a precision measuring devices

If you use the normal ruler you can only be certain your measured distance is 1.5cm

With a precision ruler you can be certain, that your measured distance is something like 1.500cm

Collapse
 
savagepixie profile image
SavagePixie

Oh, so it's a measurement thing.

Interestingly enough, technically, according to Wikipedia we have no way of knowing whether any zero to the right of the last non-zero digit is significant or not, regardless of the presence of decimals. So the exercise is still not quite right.

Thread Thread
 
schwepmo profile image
schwepmo

I feel like the exercise is fine. It defines a definite rule for deciding on which trailing zeros are significant and which aren't.