Worked Examples
 Observe the following chain of numbers carefully and answer the questions.
5 
3 
7 
7 
3 
4 
2 
6 
3 
7 
2 
7 
1 
3 
7 
7 
3 
7 
3 
4 
3 
2 
3 
7 
6 
1 
3 
7 
 How many 3s are followed by 7 but are not preceded by 1?
 2
 3
 4
 5
 If all the 2s and 6s are dropped, which number is exactly between the 11^{th} number from the left and the 15^{th} number from the right?
 1
 3
 4
 7
 How many pairs of consecutive numbers if added together amount to eight?
 2
 3
 4
 5
 Beginning with the first number, make groups of four numbers and add the numbers in each group together. Which group has the highest sum?
 1^{st}
 3^{rd}
 4^{th}
 ^{}7^{th}
Analysis:
 Mark all 3s in the given number chain, which are followed by 7 and not preceded by 1.
5  3  7  7  3  4  2  6  3  7  2  7  1  3  7  7  3  7  3  4  3  2  3  7  6  1  3  7 
 On dropping all 2s and 6s, the chain of number appears as under:
5  3  7  7  3  4  3  7  7  1  3  7  7  3  7  3  4  3  3  7  1  3  7 
 Sum of each pair of consecutive numbers is furnished below:
8

10

14

10

7

6

8

9

10

9

9

8

4

10

14

10

10

10

7

7

5

5

10

13

7

4

10

 If four numbers from the beginning are grouped together, we get 7 such groups. The sum of numbers in each group is as furnished below:
22

15

19

18

17

15

17

 Write the first 13 letters of English alphabet in the reverse order. Then write the remaining 13 letters in the reverse order.
 How many letters are there between C and T?
 7
 16
 8
 15
 Which is the letter exactly in the middle of the 15^{th} letter from the right and the 18^{th} letter from the left?
 B
 M
 X
 Y
 Which is the letter to the right of the 20^{th} letter from the right?
 F
 H
 E
 I
Analysis:
Write all the 26 letters of English alphabet as suggested in the problem.
M

L

K

J

I

H

G

F

E

D

C

B

A

Z

Y

X

W

V

U

T

S

R

Q

P

O

N

 We observe that there are 8 letters between C and T.
 B is the 15^{th} letter from right and V is the 18^{th} letter from left. The letter Y is in the middle of B and V.
 G is the 20^{th} letter from right and the letter F is to the right of G.