About this site

The site mainly started around the idea of an online generator of exercises to practice the soroban. It evolved a bit with the addition of pages with mental calculation software; then the virtual soroban and its "tutorials" and the possibility to get an operation being displayed on the virtual soroban. A forum was needed to overcome the limitation of disqus, which is a great commenting system anyway.

Donations welcome

You don't need a Paypal account if you don't have one

Since we changed hosting in August 2021 to use pythonanywhere.com, we are now billed 6€ per month. This is without counting for the domain name cost which is about 16€ per year. The total cost is then around 88€ per year.

Any donation is welcome to cover those recurring costs. I will also take them as a tip for the work I made on this site. We thank any donor in advance for their good gesture.

  • Total donation received for 2024 so far: 54€

You may need a currency converter from/to €, you could give a try to the one at xe.com. Beware that Paypal does not use the same exact exchange rate that xe.com

Buy me a coffee instead ?


May be you want to buy me a coffee instead ? Go to my ko-fi page.

In fact, you will be able to change the amount of your donation, if you wish to.

Bitcoins accepted here

bitcoin logo

We are now accepting donations in bitcoins.

You can either use the new Bech32 SegWit address ::bech32::. This is the preferred method.

However, for backward compatibility, we provide also a P2SH address ::p2sh::

qrcode for bech32 bitcoin address
Bech32 bitcoin address
qrcode for p2sh bitcoin address
P2SH bitcoin address


This is what is used to create this site

pythonanywhere logo google analytics logo Sendgrid python logo reportlab logo html5 logo flask logo jquery logo bootstrap logo vscode logo git logo archlinux logo

The last revision of the code of the site has the git HEAD commit id ca311be


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