# Significant Figures

## Significant Figures

Significant figures in the measured value of a physical quantity tell the number of digits in which we have confidence. Larger the number of significant figures obtained in a measurement, greater is the accuracy of the measurement. The reverse is also true.

The number of significant figures in a result is simply the number of figures that are known with some degree of reliability. The number 13.2 is said to have three significant figures. The number 12.30 is said have 4 significant figures.

The following rules are observed in counting the number of significant figures in a given measured quantity.

1) All non – zero digits are significant:

Example: 42.3 have three significant figures.

243.14 have five significant figures.

2) A zero becomes significant figure if it appears between two non – zero digits:

Example: 5.03 have three significant figures.

4.004 have four significant figures.

3) Leading zero of the zeros placed to the left of the numbers is never significant:

Example: 0.543 have three significant figures.

0.008 have one significant figure.

4) Trailing zeros or the zeros placed to the right of the number are significant:

Example: 4.330 have four significant figures.

433.00 have five significant figures.

5) In exponential notation, the numerical portion gives the number of significant figures.

Example: $$1.32\times {{10}^{-2}}$$ have three significant figures.

$$1.45\times {{10}^{4}}$$ have three significant figures.