Significance of 3 and 1/2 digit dispay :

1. The number of digit positions used in a digital meter determines the resolution .
2. Hence a 3 digit display on a DVM for a 0 - 1 V range will indicates the values from 0-999mv with a smallest increement of 1mv.
3. Normally a fourth digit capable of indicating a 0 or 1 ( hence it is called asHalf Digit ) is placed to the left .
4. This permits the digital meter to read values above 999 up to 1999 to give overlap between ranges for convenience a process called over ranging .
5. This type of display is called as$3 \dfrac{1}{2}$ digit dispaly