The abacus was a great invention in ancient China and has been called by some Western writers "the earliest calculating machine in the world".

Everybody in China uses an abacus in spite of any electronic calculator. I tried to use it but I started having problem when I was trying to get the logarithm of any number to base e.

No, really, I bought one and even though I don’t think I’m pretty stupid, I was unable to find where the batteries were placed. May be the one I bought worked with solar energy but also I couldn’t find any cell. So, I put it in the trash.

I think I’m lacking in education, “’cause” in the owner’s manual I could read:

“Abacuses are easy to make, handy to carry around and quick to give the answers provided one knows how to move the beads. They have been in use, therefore, down to this day”.