An unexpected pleasure of making popular YouTube videos is meeting fans - some of who make great efforts to visit us in person.
AIDAN THE ADDICT
First, here is Aidan, a 10-year-old from here in the UK diagnosed with Aspergers Syndrome and described by his dad Stuart as a "Numberphile Addict".
In an introductory email, Stuart explained: "We stumbled across the Numberphile videos and website, and he has started consuming them at a rate of knots. He has even started doing his homework whilst filming himself as a mini-video and 'presenting' what he is doing in the format of your films."
Aidan and his family visited the University of Nottingham and met various people from the videos - Ed Copeland, Phil Moriarty, Ria Symonds, Meghan Gray and Gerardo Adesso.
Here are some pictures:
But perhaps the best picture came after the visit from Stuart:
By way of explanation, Stuart said: "Just wanted to say another HUGE thank you for yesterday; as Aidan himself said, 'to leave with gold nano-particles, his own galaxy, the solution to the Rubik's cube, a good piece of homework from Ed, and of course THE brown paper, it was quite a good day!'
"I'm sure you'll already know this, but 'quite a good day' for a child like Aidan is the utmost of praise!
"I've attached an image of our journey home, which a couple have seen on twitter, but I think it sums up the day perfectly - Aidan is content with Leonard (his pet Lion!), and the only other time we have seen this look of contentment on his face was on the way home from his ASD assessment 6 months ago when he finally had a 'reason' to explain things to others!"
BIG FAN QUARRIE
Another young Numberphile fan is nine-year-old Quarrie.
His family was visiting London from the US - but made a special trip up to Cambridge to see Quarrie's favourite YouTuber, Dr James Grime.
James showed Quarrie around his workplace and they even spotted Stephen Hawking!
Here are some pics from Quarrie's dad, Tim:
Tim told me in an email: "James was incredible. I have never seen Quarrie smile so much. You know, James even took him up to see Stephen Hawking, and still, I think he was more impressed with James. That says a lot from a kid like Quarrie."