cantor software package provides interface for mathematical applications, you can install in your Debian 9 (Stretch) by running the commands given below on the terminal,
$ sudo apt-get update $ sudo apt-get install cantor
cantor is installed in your system.
Make ensure the cantor package were installed using the commands given below,
$ sudo dpkg-query -l | grep cantor *
You will get with cantor package name, version, architecture and description in a table
| Distro | Debian 9 stretch |
| Section | Mathematics |
| Package | cantor |
| Version | 4:16.08.2-1 |
| Description | interface for mathematical applications |
| Sub Section | Math |