First off, nice signature . It works quite well on the mozilla start page
If a 2 is on top, then you will only win if the second card is a 1, chance of this happening: 1/10*1/9=1/90
If anything else is on top, you will only win if 1 is either the second or third card, chance of this happening is:
(chance of second card being 1) + (chance of third card being one)
= (8/10 * 1/9) + (8/10 * 7/9 * 1/8)
= 8/90 + 7/90
Add all those together to get:
But make sure to CHECK MY ARITHMETIC!!!!!!!!!!!