Solution:

121

Explanation
Tables consist of squares of the number from 4 to 12.
11^2 = 121.

Solution:

28745

Explanation

New Number = (Last Number +1 ) * 9
and Then New Number = (Last Number - 1 ) * 8 and so on.

i.e
1
(1+1) * 9 = 18
(18-1) * 8 = 136
(136+1) * 7 = 959
(959-1) * 6 = 5748
(5748+1) * 5 = 28745
(28745-1) * 4 = 114976
(114976+1) * 3 = 344931

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:

118119

Explanation:
Number are generated as below
1 2
3 4
1 x 4 + 2 = 6 , 2 x 3 + 1 = 7 => 67

3 4
5 6
3 x 6 + 4 = 22, 4 x 5 + 3 = 23 = 2223

5 6
7 8
5 x 8 + 6 = 46, 6 x 7 + 5 = 47 = 4647

7 8
9 10
7 x 10 + 8 , 8 x 9 +7 = 7879

Based on above pattern, desired number will be calculated as :
9 10
11 12
9 x 12 + 10 = 118, 10 x 11 + 9 = 119 = 118119

Solution:

3! + 15 + 9 = 30

Explanation:
3! = 3 * 2 * 1 = 6
6 + 15 + 9 = 30

Solution:

73 & 48

Explanation:
We can get the number on the left by adding numbers above it and subtract the sum by 5. i.e.
8 + 11 - 5 = 14
14 + 10 - 5 = 19
19 + 16 - 5 = 30
30 + 21 - 5 = 46
46 + 32 - 5 = 73

Right column = left number above it + 2 => 46 + 2 => 48

Solution:

17

Explanation :
The relationship holds for below formula :
pow(x,3) - pow(x,2) - 1
=> 9*9*9 - 9*9 - 1
=> 729 - 81 - 1
=> 647

Similarly,
17*17*17 - 17*17 - 1
=> 4913 - 289 - 1
=> 4623

Solution:

26

Explanation:
14 = 1^2 + 2^2 + 3^2
21 = 4^2 + 1^2 + 2^2
29 = 4^2 + 3^2 + 2^2
26 = 3^2 + 4^2 + 1^2

Solution:

20

Explanation :
The sequence is given in the puzzle is :
11 15 19 12 16 ? 13 17 21 14 18 22

Let's break the given series as below:
11 15 19
12 16 ?
13 17 21
14 18 22

Now read the number from left hand side from top to bottom as :
So the number that will replace '?' is 20.

Solution:

9 - 8 + 76 - 5 + 4 + 3 + 21 = 100


Other ways of making number 100 (withiout using number 32)
98 + 7 + 6 - 5 - 4 - 3 + 2 - 1 = 100
98 - 7 - 6 - 5 - 4 + 3 + 21 = 100
9 - 8 + 76 - 5 + 4 + 3 + 21 = 100
98 - 7 + 6 + 5 + 4 - 3 - 2 - 1 = 100
98 + 7 - 6 + 5 - 4 + 3 - 2 - 1 = 100
98 + 7 - 6 + 5 - 4 - 3 + 2 + 1 = 100
98 - 7 + 6 + 5 - 4 + 3 - 2 + 1 = 100
98 - 7 + 6 - 5 + 4 + 3 + 2 - 1 = 100
98 + 7 - 6 - 5 + 4 + 3 - 2 + 1 = 100
98 - 7 - 6 + 5 + 4 + 3 + 2 + 1 = 100
9 + 8 + 76 + 5 + 4 - 3 + 2 - 1 = 100
9 + 8 + 76 + 5 - 4 + 3 + 2 + 1 = 100