One I learned from my 9 year old daughter, I never knew this.
For multiples of 9, up to 10x9
eg:
what is 9x3?
here was her answer. I will only provide the equations she used, because her description was too funny to recount.
9x3
3-1=2
2+7=9
remove the + sign
answer
27
So I fiigured it out, works on 9x1 up to 9x10. She said they taught it to them, only works on 9's. Still, I never got this in school. I was quite impressed not only by her accomplishment of it, but also the simplicity of the teaching method involved.
I don't think her teacher is from Kentucky though.