The Number of Significant Figures In

Q. The Number of Significant Figures in 0.06900 is (a) 5 (b) 4 (c ) 2 (d) 3 

Answer- (b) 4

The prefixing and suffixing of zeros in decimal and average numbers have significant figure values.  

Significant figures are measured values of a physical quantity that tell the digits in which we have confidence. The larger the number of significant figures obtained in the measurement, the greater the accuracy. 

Rules for Solving Significant Figures

• The first rule is that all non zero digits are likewise viewed as significant numbers :1, 2,3,4,5….
• The second rule is Zeros between nonzero digits are also considered significant: 102,20005, 25020 ….
• Now the third rule can be given as :

A final zero or trailing zero in the    

a decimal portion only is significant 

Example : 0.500 or 0.632000 the 

zero are not significant. 

• Fourth and the significant rule is that in a number, regardless of a  decimal point, trailing zeros on the right of the last non zero digits are significant if they are justified by the precision of their deduction: 252,0000, 5.021332, 6.9003…..

Rules for for Addition and Subtraction

• Count the number of significant figures in the decimal part of each number in the problem or sum. 
• Add or subtract in the normal way. 
• Your answer may have no more significant figures to the right of the decimal than the least number of significant figures in any number in the problem.  

Rules for Multiplication and Division

• The least number of significant figures in any problem number determines the number of significant figures in the answer. (You are currently looking at the full number, not just the decimal portion). 

Example: 5.26 has three significant figures

6.1 has two significant figures. 

Now according to the rule, it can be said that the number 0.6900, has four significant figures as zeroes before the non zero numbers are considered insignificant.