Hi,
Well, actually, when I was a kid & we started learning multiplication, I noticed a very nice relation for the number 9.

If you multiply any number with nine, starting from 2 to 9 you can notice the following:
Easily, 1 * 9 = 9
Now for numbers from 2 to 9
You choose the number you want to multiply with nine, 1st you subtract one from it, this new number is your 10's.
Now the same number that you still want to multiply with 9, you subtract it from 10, the new number is your one's
Example:
2 * 9 = 18
In the way I discovered in elementary [Notice: I do not memorize the number 9 multiplication table & I have never did :) ]
For ten's --> 2 - 1 = 1
For one's --> 10 - 2 = 8
So, its 18

3 * 9 = 27
-------------
3 - 1 =  2
10 - 3 = 7
= 27
-------------
-------------
4 * 9 = 36
-------------
4 - 1 = 3
10 - 4 = 6
= 36

till 9*9 = 81
-------------
9 - 1 = 8
10 - 9 = 1
= 81

& this is my story @ elementary school where I discovered this relation, & I still use it till now.

Hope you like it.

Sincerely: Ahmad Hadeed

no its all the time ,
as long as u multiply by the numbers range (1, 10)