All those the number that is starting from a nonzero digit and expressing the number to require a degree of accuracy is recognized as significant figures. Of a number that is used to express it to the required degree of accuracy, starting from the first nonzero digit. Now let’s suppose any random number. If a digit that is instantaneously present to the right side of the latest significant figure is larger than 5 and followed by any nonzero digits, then we will simply add 1 to the last significant figure and increase it by 1. This process is known as rounding off.
Significant figures calculator and rounding number calculator provide the opportunity to make calculation simple and express the numbers in standard form effortlessly.
Example of significant figures
Numbers  Number of significant figures  explanation 
0.00682  There are 3 significant figures; 682  Present zeros are not significant in this example. You can take help from a significant figure calculator online to clarify it for more understanding. 
1.072  There are four significant figures; 1072.  Zero is present between two nonzero digits that is why it will also be considered as significant. 
300  There is only 1 significant figure, that is 3.  There is no specified decimal point; therefore, zeros will be considered as nonsignificant. For instance, in the case of “300.” There are three significant figures because of the presence of decimals after zeros. 
Example of rounding number
 
Difference between the rules for Significant Figures
Significant figure rules  Rounding off number rules 
All those numbers that are recognized as nonzero numbers are significant figures. You can also take help from any sig fig calculator online to identify the nonsignificant and significant zeros.  Once you have the number to round off, just look at the digits that are present on the right side. If the digit is 1 2 3 4, then you will not change it as it is less than 5. 
All those Zeros that are present in between the two nonzero digits will also be considered as significant.  If the digit is greater than 5, then you will increase the number by 1. 
All the leading zeros in any given number will be considered as nonsignificant. Such as in 300, the last two zeros are nonsignificant.  In case of decimals, look at the right side of the digit, and If that digit is less than 5, just drop all digits to the right side of your number. 
Trailing zeros that are located to the right of the decimal point are significant. For example, in 1.008, both zeros are significant figures. Any online Sig fig counter is well established to label such zeros as sig figs.  If the digit after the decimal point is larger than 5, we will just add 1 to the rounding digit. All those digits present to the right side will be dropped off. 
Trailing zeros that are present in any whole number even with the decimal point are sig figs. The use of the sig fig calculator is a wellorganized way to deal with such numbers without any mistake.  There are some categories to round any given number. Consider 765.3682 it will be rounded off as follows:
