Significant Figures Rules – Examples

At the end of the articles, you will know Significant Figures Rules with Examples of addition and Subtraction. Let’s get started. The total number of digits in a number including the last digit, whose value is uncertain, is called number of significant figures. For example: 10.421 has five S.F.

Significant Figures Rules

  1. All non-zero digits as well as zeroes between non-zero digits are significant. For example: 15004 has five S.F.
  2. Zeroes to the left of first non-zero digit are not S.F. For example: 0.0028 has two S.F.
  3. If a number ends in zeroes but  these zeroes are to the right of decimal point, then these are significant. For example: 2.500 has four S.F.
  4. If a number ends in zeroes but these zeroes are not right of decimal point, than these zeroes may or not be significant. For example: If  10500 is written as 1.05×104, then it has three S.F. However, If it is written as 1.050×104 has four S.F.

Significant Figures Rules Addition and Multiplication

  • The result of an addition or subtraction should be reported upto same number of decimal places as that of the term with least number of decimal places.

For example: Sum of 4.525+2.3+6.24=13.063 will be reported as 13.1.

  • The result of multiplication or division should be reported upto the same number of S.F. as are present in least precise number.

For example : 4.327×2.8=12.1156 will be reported as 12.

Rules For Rounding Off

It implies as follows

  • If the digit just next to the last digit to be retained is less than 5, the last digit is taken as such and all other digits to its right are dropped. For example: 1.234=1.23.
  • If the last digit is greater than 5, the digit to be retained is increased by 1 and other digits on its right are dropped. For example: 1.236=1.24.
  • If the digit just next to the last digit to be retained is equal to 5, the last significant figure is left unchanged if it is even and is increased by 1 if it is odd. For example: 1.235=1.24, 1.225=1.22.

Significant Figures Examples

Examples Significant Figures
96,002 g  5
0.044 g 
200 g
4.7200 km
82.0 m 
5.009 m 
306 km  3
0.00783 kg 

This is all about the basics of Significant Figures Rules with Examples of addition and Subtraction.

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