What is the name of the movie

I watched the movie a couple of times in Soviet times, but I don't know the title. And the worst thing is that I don't remember any of the famous actors there. Or you can find the last name on Kinopoisk.
So the plot... there was this guy who could do calculations and multiplications in his head. And a guy gave him a wristwatch. And then they disagreed and the guy started beating him up and said, "Now let's multiply...".
I think there was something mentioned about Pushkin...

I remember seeing something similar on soap today. Only they weren't going to kill him there.
The aliens came, and he really wanted them to take him with them to other worlds. Well, they decided to give him a brain efficiency test.
There was a rather strange calculator, especially for those times - smooth figures, times new roman font, yellow figures on blue background, first it says ""wait for answer"", then - ""don't wait for answer"".
But I can't remember what it's called.

I remember seeing something similar on soap today. Only they weren't going to kill him there.
The aliens came, and he really wanted them to take him with them to other worlds. Well, they decided to give him a brain efficiency test.
There was a rather strange calculator, especially for those times - smooth figures, times new roman font, yellow figures on blue background, first it says ""wait for answer"", then - ""don't wait for answer"".
But I can't remember what it's called.