Hey @gregmat
I have doubt in this question as we are arranging the letters and you mentioned order is not important . suppose, we are choosing minimum 15 then there might be two possibility for which the question holds true. i.e AB can also be placed as BA which gives 2 possibility and thus 2/105 which is not less than 1 percent.
correct me if I am wrong. Thanks
If you treat AB and BA as two different pairs, then the base of 2/105 mentioned by you is actually 105 times 2 as A(2, 15) = 15*14 = 210 = 105 * 2. Then the answer will still be 2/210 = 1/105
Thank you buddy!
u r welcome 
Let’s grow together 
No you can not.
Please look at the word “positive” right after the “different” 
But google says, 0 is a positive integer.
With no offense, have you really googled it?
Check out this page⬇️
https://www.google.com.hk/search?client=safari&rls=en&q=is+0+a+positive+%3F&ie=UTF-8&oe=UTF-8
“The number zero is neither positive nor negative”
.
