There is always a test which can challenge yourself to the limit, even though you have left school.
Suken, 数険、or refers to 数学検定試験 Suugaku Kentei Shiken.
I'm living at Johor Bahru, Malaysia and the nearest center to take it outside Japan is Singapore.
Registration will be through Eventbrite.
The center which organize it is SUPERMEDIA.
My next examination will be on this Saturday, July 9th 2016, for Suken Level 9. Passed Level 10 last year as warming up. ! :-)
Currently I'm waiting for my Adsense approval, which i will include more details soon.
For more information, visits this official websites:
Sample test questions:
Books to study:
(search for keyword: Suken)
Cheers, and do let me know if you need more information.