Answer 8—If two digits differ in only one segment, that pin must be connected to tell them apart. Labeling the segments conventionally, clockwise from A at the top and with G in the middle, at least the following five segments are needed:

1.  A to distinguish 1 from 7

2.  B to distinguish 6 from 8

3.  E to distinguish 9 from 8

4.  F to distinguish 3 from 9

5.  G to distinguish 0 from 8

 By inspection, one can show that these five are sufficient to distinguish all 10 digits.

Contributor: Tom Napier

Published January 2004