What are these toll free "Yahoo Tech Support " numbers popping up as answers to questions?

They are scammers trying to gain remote access to your computer to install malware then blackmail you into paying up to $1000 or they delete everything from your computer

Watch this video to see what happens if you speak to these criminals and allow them to access your computer

http://www.wired.co.uk/article/malwarebytes

They claim to be from Yahoo, Microsoft, Dell, Google, and other well known companies but it's all the same scam - to gain access to your computer and steal your money

They're scammers and fake. They're bots. Always report them as spam.

They are spam and scams Report or ignore them.

spammers trying to get gullible people to call them so they can try and steal personal info