I think Andrew Jackson was a terrible speller as well.
My History teacher (back when they used to teach such foolishness) told us a story on this topic.
It seems at one point Andy was a quartermaster for the Army, and his job was to inspect cases of rifles to make sure each case was complete, the rifles assembled, and in working order. When he got done with each case he would mark it..."Oll Korekt" (guess he had a bit of an accent)
You know how the military is with acronyms, so as time went on, he decided to abbreviate it, and simply marked them OK.