Solution:

If you look at the answer figure, you will see four 1x1 squares and one 4x4 square. Nobody asked you to make five 1x1 squares. Most of the people get stuck at that.

Solution:

The attached picture gives away the solution. If you can find another solution, do send us yours.

Solution:

The best way is to divide the batteries in three groups. Take three batteries in two groups each and two batteries in the third group.

In the groups with three batteries, you can have three possible combinations in each group. In the group with two batteries, you can have just one possible combination.

If you add the combinations: 3 + 3 + 1 = 7, you get the least number of pairs you must check.

Solution:

Brian is the one who speaks truth.

Adam is lying about Brian. Also Cody Is lying since Brian does not lie. Thus Brian is the one speaking truth. Any other combination will fail to come out true.

Solution:

If you notice the animated gif, you know that D, C and B are going to die. D dies directly after coming in contact with the object, C dies after being thrust by the spikes of the see-saw and B dies with the blue ball.

But consider the situation that the person at E stands for Ebola. Eventually A dies as well.

We thank 9gags for this awesome gif.

Solution:

The attached picture shows you how you can do it. If you were able to deduce any other way, feel free to comment.

Solution:

Here is a way to do it. We dont know if it can be done using some other arrangement or not. If you know, do send us.

4 | 3 | 8
9 | 5 | 1
2 | 7 | 6

Solution:

43

Explanation:
Here is the thing. You can buy any number of wings that can be divided evenly by three except for three by using the combinations of boxes of 6 and boxes of 9. (You must use at most the box of 9 and then multiple boxes of 6). Now, if there is a number that can't be divided by 3, use a box of 20. After purchasing the box of 20, if the number that remains is divisible by 3, then you are good to go. On the other hand if it is not, you will have to use a second box of 20. And the remaining number will definitely be divisible by 3.

Thus if we calculate the largest number that can't be bought is the one that requires two 20 pieces boxes before the remainder can be thinned down to a number divisible by 3. We know that 3 is the number that can't be purchased and can evenly be divisible, the largest possible number of wings that can't be bought are:
3 + 20 + 20 = 43.

Solution:

They can say this line only on Thursday.

Explanation:
Let us analyze the statement. If the person who is speaking this line is speaking truth, then the person will have to speak a lie on the next day. But if the person is lying, the next day, that person must speak truth on the next day.

If you notice here, the behavior is changing on the next day no matter what the person speaks. If we create a response table for both Jack and Rose, it will look like this:

Jack Rose
Monday Truth Truth
Tuesday Truth Lie
Wednesday Truth Lie
Thursday Truth Lie
Friday Lie Truth
Saturday Lie Truth
Sunday Lie Truth

Now as you can clearly see, Jack can say this statement on Thursdays and Sundays while Rose can say this statement on Mondays and Thursdays.

Since they are saying on the same day, the required day is Thursday.

Solution:

No one can take out any money from the taxi meter because it simply does not contain any money. It just has a timer installed that is used to decide the fare as per the distance covered.