Central Brain-teasers

When I hear about mindgames, I'm always in.
Although this event was more about the curiosity games rather then brain-teaser, it was nice. We even heard from organizer that it was soo "hot" that some of the parts were stolen during the day.. what a shame.

Ludolph's number, it's being said that if you look closely you should find your date of birth, if not you need to extend this table until you find it ;)

How you should extend this table? Here's the formula
π = (4/1) - (4/3) + (4/5) - (4/7) + (4/9) - (4/11) + (4/13) - (4/15) ...
Take 4 and subtract 4 divided by 3. Then add 4 divided by 5. Then subtract 4 divided by 7. Continue alternating between adding and subtracting fractions with a numerator of 4 and a denominator of each subsequent odd number. The more times you do this, the closer you will get to pi.
Here are the first 100 digits = 3.14159265358979323846264338327950288419716939937510582097494459230781640628620899862803482534211706798214

Some of the text was wrongly translated from English to Slovak, so it does not make sense. Especially this one was totally wrong in Slovak and no one around this table was able to understand this unless you followed the English instructions.

When doing "by 9" multiplications I was always using "in head calculation" (10*n)-n. This one is quite funny and would be nice exercise for kids in school, as well to talk about why it's working like that.

This one was hard, really hard, especially because my heir was trying to build railway.

This one is nice new rebus with pentonimo.

We learned what you can do with many kangaroos.

During the meal time I noticed this "font fail" on the menu board. I will never understand why someone will put up something like this to present their business.

More at private blog.