What can you do with the number 9?

[RemyZee]

I am not a fan of numbers in that I have dyscalculia and they are swirling blobs to me, although I truly like the IDEA of numbers. But I've just learned there are all kinds of unusual, unexpected, absorbing things a person can do with the number 9, and it's given me an appreciation of the mysteries of numbers--though the calculations are difficult for me to understand because my noggin stops working and starts rebelling around the count of 15. I thought I would put this thread up to ask, for whoever is into numerals: what are some weird and whacky things you can do with 9?.

 

[Jumpinbare]

Add 9 to 9 and you get 18 add 1 and 8 and you get 9
add 9 to 18 and you get 27 add 2 and 7 and you get 9
add 9 to 27 and you get 36 add 3 and 6 and you get 9
this pattern continues all the way to 81