Is this also possible in Czech... "Myslím, že týden má sedm dní"?
Also, I didn't try "has" in the English translation, but I think "has" may be used more often than "is."
UPDATE - - - - I just tried "has seven days" and it was accepted. (June 2018). If I have a chance, I'll try "má" on the Czech side.
Yes, the meaning in English is pretty much the same. But I think the Czech sentence in your example MIGHT be something more like -- and I am making this up, so it could be totally wrong -- "Myslím, že to je sedm dní v týdnu." And I'm also thinking that the "Czech way" of saying how many days are in a week MIGHT just be what's shown at top of the d´page, rather than something like what I made up...