11. Within each exchange, random digits were added to form a complete telephone number, thus permitting access to listed and unlisted numbers. 12. Within each exchange, random digits were added to form a complete telephone number, permitting access to both listed and unlisted numbers. 13. Within each exchange, random digits were added to form a telephone number, thus permitting access to both listed and unlisted numbers. 14. For each exchange, the final four numerals were formed by random digits , thus permitting access to both listed and unlisted numbers. 15. And it is perhaps a poignant sign of the times that now when random digits disappear from people's lives they are mourned. 16. Within each exchange random digits were added to form a complete telephone number, thus permitting access to both listed and unlisted numbers. 17. Within each exchange, random digits were added to form a complete telephone number, thus permitting access to both listed and unlisted numbers. 18. Within each exchange, random digits were added to form a complete telephone number to permit access both to listed and unlisted numbers. 19. Some modern tests plot random digits as points on a three-dimensional plane, which can then be rotated to look for hidden patterns. 20. Within each exchange, random digits were added to form a complete telephone number, thus permitting access to listed and unlisted numbers alike.
