Define Significant Figures
The significant figures of a given number are those important digits, which carry the meaning
contributing to its precision. For example, the number 5.678 has four significant figures. Significant
figures provide accuracy to the numbers. Significant figures can also be termed as significant digits.
Significant Figure Rules
The rules for significant figures are as follows:
(i) All non zero digits are significant. 12365 contains 5 significant figures.
(ii) All zeros occurring between the two non zero digits are significant. 109.0087 contain 7 significant
figures.
(iii) All zeros to the right of a decimal point and to the left of a non-zero digit are never significant.
0.00987 contained 3 significant figures.
(iv) All zeros to the right of a decimal point are significant, if a non-zero digit does not follow them.
20.00 contain 4 significant figures.
(v) All zeros to the right of the last non-zero digit after the decimal point are significant. 0.0089700
contains 5 significant figures.
(vi) All zeros to the right of the last non-zero digit are not significant. 9080 contains 3 significant figures.
(vii) All zeros to the right of the last non-zero digit are significant, if they come from a measurement.
1090 m contains 4 significant figures.
Significant Figures Examples
Below you could see significant figures examples, for adding significant figures, multiplying significant
figures and dividing significant figures.
Solved Examples
Question 1: Identify the number of significant figures from the following.
48, 0.048, 5.4880, 6002, 4800
Solution:
48 - The number 48 is a non-zero number that has two significant figures.
0.048 - Zeroes placed before the other numbers are not significant figures and the number of significant
figures in 0.048 is two.
5.4880 - Zeroes placed after the other numbers but after a decimal point are significant figures and the
number of significant figures in 5.4880 is five.
6002 - The number 6002 has four significant figures because the Zeroes placed between the figures are
always significant.
4800 - The number 4800 may have at least two significant figures. It also has three and four significant
figures. That is:



4800 - 4.8 x 103 has two significant figures.
4800 - 4.80 x 103 has three significant figures.
4800 - 4.800 x 103 has four significant figures.
Question 2: Add the numbers 7.32, 7.21, and 23.96 and fund the number of significant figures in the
solution.
Solution:
The given numbers are 7.32, 7.21, and 23.96.
The number 7.32 has three significant figures.
The number 7.21 has three significant figures
The number 23.96 has four significant figures.
Adding the numbers, we get:
7. 3 2
7. 2 1
2 3. 9 6 +
_______
3 7. 4 9
Therefore, the solution is 37.49.
37.49 can be rounded to 37.5
Therefore, the number of significant figures in 37.5 is three.
Question 3: Calculate the number of significant digits from the following calculations. 5.2 x 103 x 6.732 x
102
Solution:
When we divide or multiply the numbers the number of significant digits in the result is the equal as the
least number of significant digits in any of the divided or multiplied terms.
5.2 x 103 has two significant digits, 6.732 x 102 has four significant digits, and the result will have two
significant digits.
The number 7.5 x 106 is rounded to 7.5 x 106 since the number to the right of the last significant digit <
5.