Roberto Abraham Scaruffi

How do I prove that the root of every prime number is irrational? Jessica Su, CS PhD student at Stanford 129 votes If it were rational, you could write [math]\sqrt{p} = a / b[/math], and[math]a^2 = b^2 p[/math]. Every square number has an even number of prime factors, because [math]a^2 = \mbox{(factors of a)} \cdot \mbox{(factors of a)}[/math]. So the left side of the equation has an even number of pri... Read More »

What picture represents the Chinese people? Anne Hathaway 1.8k votes This is China’s river while this is also china’s river ... Read More »

How do top students study? Larry Hill, Retired Engineer 502 votes Without generalizing, I can give you one specific case which you can do with as you will. As a girl, my wife needed a telescope to see the bottom of the middle class. In ... Read More »

What should every foreigner know about your country? Why? Lucas Lundström, expert, specialist and professional. 1.2k votes Sweden. We don't have polar bears. (Norway actually do, since they own the islands of Svalbard further north.)... Read More »

How do actors bulk up so quickly for movie roles? Jason Neff, Former Captain in the U.S. Army. Fitness enthusiast. Researcher. Trained vocalist. 544 votes I'm answering this question as someone who has also asked it because I find it fascinating. We watch these transformations and read news articles that says 'so-and-so actor... Read More »

If I volunteer to get inside a black hole, can NASA let me do it? Viktor Toth, IT pro, part-time physicist 479 votes If you have the technology to get to the nearest confirmed black hole, I doubt NASA, the United States military, or indeed any power on this Earth can stop you even if they... Read More »

If the six-digit number 213X23 is a multiple of 7, then what is the value of X? Ashish Kushwaha 203 votes I can keep breaking it into parts divisible by 7: [math]213X23 = 210000 + 3X23[/math] [math]= 7k_{1} + 21 + 3X02[/math]... Read More »

How can I increase my focus? Achintya Prakash 778 votes I see productivity and focus as two distinct things, albeit interrelated. I believe it is possible to boost productivity with a somewhat minimal increase in the inherent fo... Read More »

What is the weirdest or most disturbing thing that a kid has said to you? Scott Paglia, North By North Whatever 1.8k votes My daughter and I were reading on the couch one Sunday morning. It was raining outside. We were wrapped up warm in a blanket. She had a cup of tea. I had that perfect ameri... Read More »

I'm having a problem that whatever I do, I want to be a prodigy in that. Like when I play football, I want to play like Ronaldo, and when I do programming, I want to code like Peter Mitrichev and etc. When I can't do that, I feel depressed and sad. What should I do? Arti Gupta 5.4k votes I have a daughter 7 years old. I just started her guitar classes and she cried after her first class as she could not play well. She wanted to play like Amin Toufani on day... Read More »