The total number of digits in a measured physical quantity is called the number of significant figures. The number of significant figures refers to the precision of a measured quantity and may be defined as follows:

The number of significant figures in a measured physical quantity refers to number of digits written, including the last one whose value is uncertain.

Rules for Determination of Significant Figures:

[i] All non-zero digits are significant.

For example: 146 cm has three significant figures.

[ii] The zeros placed to the left of the first non-zero digit in the given physical quantity are not significant.

For example: 0.56cm has two significant figures.

[iii] The zeros placed to the right of the decimal point are significant.

For example: 15,0cm has three significant figures.

[iv] The zeros placed between two non-zero digits are significant.

For example: 6.08cm has three significant figures.