The insight of Significant Figures you don’t want to miss

Hye, looking for a detailed description of significant figures? If yes, then you are in the right place because we have designated this article to provide you with all the required information about significant figures. 

Significant figures can be marked as all the non-zero digits present in a numerical value or number that makes it precise and accurate. For example, a value ‘25’ has two significant figures, 2 and 51. On the other hand, a value ‘025’ also has two significant figures because of the trailing (placeholder) zero. 

Usually, all of the numbers except zeroes can be counted as significant figures. Anyhow, there are some zeroes that are marked as significant figures. Such zeroes can be those that come in between two non-zero digits as in 203, the 0 comes in between 2 and 3, so it is a significant figure. Those zeroes that are placed at the right of a decimal are also significant figures such as if we have a value ‘0.25’ then there are three significant figures as the trailing zero at the right of the decimal is significant. Or if we have a value ‘250.’ then this zero is also significant as there’s a decimal above it. 

Rules for Significant Figures

On the basis of the above-mentioned facts, we can deduce some rules for significant figures that are given below:

  • Non-zero digits are significant figures
  • Zeroes (without a decimal) are non-significant 
  • Zeroes at the right of a decimal are significant
  • Zeroes between two non-zero digits are significant 

These are the basic rules for finding significant figures. You should keep these in mind while looking for a significant figure in the value.

Now, let’s move ahead to discuss the role of rounding in significant figures calculation.

Significant Figures and Rounding

The numerals (larger ones) are rounded off so that their precision can be decreased. It means that we can simplify and shorten any number by rounding it off. Likewise, we can round off to the significant figures.

You can round off a number both as per the desired numbers of significant figures as well as per the decimal places from 1 to 9.

For example, we want to round off 58.669 to the 2 significant figures then it’s rounded off value will be 59. To round it off to the 2 significant figures, we look for the digit after the first non-zero digit. The value of the digit after the first non-zero digit is increased by 1 as it is greater than 5. It means we added 1 number to 58 as the digit next to the 8 in 58 is 6 that is greater than 5.
Whereas if the digit next to 8 is supposed to be 4 (that is less than 5) then there would be no increase in the value of 58.

Let’s make it look simpler by stating the method of rounding to one significant number:

  • Look for the first non-zero digit
  • Then look for the number next to it 
  • If it is greater than 5 then round up (increase the digit next to the first non-zero digit by 1)
  • If it is less than 5 then round down (value won’t be changed)

Likewise, if you want to round off to the second significant figure then look for the digit next to the first non-zero digit. The place of digit moves on with respect to the place of significant figures. So, this is the manual way of calculating significant figures as well as rounding to significant figures. It seems like it is quite mind-messing and time-consuming as well. If you want to save your time and energy then you can use the online sig fig calculator and rounding calculator that are fast and efficient in calculating significant figures as per the given input.

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