Header image of a close-up of a soroban


Mental calculation a simple tool made, to practice anzan - mental calculation made by visualizing a soroban, the japanese abacus.



Configuration file

mentalcalculation saves its settings in a configuration file: On Linux/or any unix-like


On Windows Vista and above


You might need to change the options of the Windows explorer to be able to see hidden files and directories to be able to access the configuration file.

You need to run mentalcalculation (and close it), at least once so that the configuration file is written to disk.

Note: It does not do anything to the Windows registry at all !


The default configuration file looks like this:

; comments are lost after mentalcalculation starts




You can change font and background colors in the [GUI] section. Change font_color and/or background_color to valid HTML color codes or use explicit name.

If you look for a way to choose a color, you could use the color picker of your favorite graphic software, or go online at https://www.colorpicker.com/, or https://html-color-codes.info/.


One can use a custom font for the display of number. Add a font variable in the [GUI] section. The variable should only hold a family font name. For example:

font=Times New Roman


Change annoying_sound variable in the [Sound] section to true to get a sound every time a number is displayed on screen.

The sound is played only if you don't use the speak synthesis system.

By default, the file called annoying-sound.mp3 in the sound directory of mentalcalculation is used. You can change it to any sound you like.

Plus sign

One can remove the + sign in front of numbers if using subtraction by using this snippet in the conf. file


in the [General] section of the mentalcalculation.ini

Tracking Usage

With the 0.3.5 release, every time you launch mentalcalculation, it tries to reach www.sorobanexam.org/mentalcalculation?ping=UUID. The UUID is a randomly generated uuid v4. No information is sent. It just allows us to gather statistics about the usage of this software and know if people only download it once and never use it again, or if it is really used often.

You might not like that tracking behavior, so you can opt-out. In mentalcalculation.ini, you can add a line:


in the [General] section; you can also use any of the following values: no, No, none, None, false, False, optout or leave it empty.

Or if the line is already there, just change the value of uuid to one of the string mentionned above to opt-out.

Fail-safe mechanism

There is a fail-safe mechanism that allows mental calculation to safely fail when it does not find one of its resources files. So, if you don't like the smileys/emoticons or the sounds, you can safely delete/rename them on your harddisk (img/sound directories), and mentalcalculation will continue to work without them.


I would like to thank the Tango project from which I borrowed some icons and the GNOME project (gnome-media, gnome-audio) for the sound files I use.

Soroban image courtesy of burlie (@Flickr) see http://www.flickr.com/photos/burls/