Solution:

2

Explanation:
This is one of the easy number series riddles in which you just need to replace the alphabets from A to Z with 1 to 26.
i.e
A = 1
B = 2
.......
.......
.......
Z = 26

So considering 1st part of equation
D = 4 , W=23 and sum = 27

In a similar fashion.
U21, L=12 and sum = 33.

In last part
G = 7 , O = 15 and sum = 22

Therefore answer is 2.

Solution:

The woman told him to take out one nut each from the rest of the wheels and use them.

Solution:

12 steps:

Steps 11 Liter jug 6 Liter Jug
1. 11 -
2. 5 6
3. 5 0
4. 0 5
5. 11 5
6. 10 6
7. 10 0
8. 4 6
9. 4 0
10. 0 4
11. 11 4
12. 9 6 ==> i found 9 liter in 11liter jug(as required)

Solution:

They used the planks in the manner that is shown in the figure.

Solution:

If the man killed himself, he would not have been able to rewind the cassette. Thus it is clear someone else killed him.

Solution:

This puzzle has no answer if you are considering this figure in a 2d domain. However if you follow it on a three-dimensional plane, you can do it like shown in the figure given.

Solution:

2, 3, 10 and 10
To maintain the difference of eight and keeping in mind the third and fourth hint, the first and third cards can be 2 and 10 or 10 and 2. But keeping in mind the first hint, we know that the first card is 2 and the third is 10. Similarly, if we see the fifth hint, the difference between the second and fourth card should be 7. Thus we know that the second card is 3 and the fourth card is 10.

Solution:

Solution can be verified from the picture below.

Solution:

Since the knife was in her hand which implies that she was planning to kill her husband "Inspector Montalbano".

Solution:

31

Explanation:
Ramanujan lighting the candles in binary.
11110 =30
11111 =31

Solution:

"World War I" was named after after "World War II"