I'm going to be showing you some tips and techniques in solving Sodoku puzzles. Our next strategy is a medium level strategy called double pair. In this example, we'll take a look at these columns here and we're going to look for the number 2. You can see that the number 2 can only be in these areas here, which means that that'll have a 2 and that'll have a 2, which means that 2 has to be in the middle here. You can see by using our notations here, if 2 cannot be there, this will have to be 7. So you'll be able to put the 7 in there and then work your way from there. As you can see because 2 has to be here or here using up these squares. So no 2 can be in there. No 2 can be in here. 2 will have to be in the middle here solving the problem for the 1-9 in the cube and in the colums. When you take a look at that, that's the pairing of it. Since it has to be in this area here, the thrid one, the 2 has to be in the middle. By using that is another way of knowing that you have to subtract rather to get where you have to be in knowing if 2 can not be in this spot here, that has to be 7 using logic that way. You can go from there to do the rest of the the problem there. As you can see, as the puzzles progress, so do your strategies in solving them. In our next clip, we'll be looking at multiple line strategy and other medium level strategy in solving Sodoku puzzles.