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5. The sum of the digits of a 2-digit number is 7. If the digits are reversed, the new number formed
decreased by 27. Find the number.
6. Find the values of the letters in each of the following and give reasons for the steps involved.

(a) 2 A B (b) 1 2 A (c) A B (d) A B
+ A B 1 + 6 A B × 6 × C
B 1 8 A 0 9 B B B 2 7 0

Number Puzzles and Games

Coding and Decoding

Coding is a method used to convert a piece of information into another form using a specific
pattern, rule, or system. It’s a technique for communicating with the recipient in which only the
sender and the recipient are aware of the meaning. In this process, the sender sends the message
in an encrypted way using codes and the recipient uses the following process to decode or decrypt
the message:

Step 1: Observe the alphabets or numbers given in the code carefully.
Step 2: Find the sequence it follows, whether it is ascending or descending.

Step 3: Detect the rule in which the alphabets, numbers, or words follow.
Step 4: Fill in the appropriate letter, number, or word in the blank given and decode the message.
For example, in a coding language, if A is coded as 2, B is coded as 3, and so on. Then, find the
code for WINNER in that language.

Since, the code for A = 2(1 +1), code for B = 3 (2 + 1), and so on. Therefore, first observe the alphabet
with their corresponding numbers, i.e.,

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27

Therefore, code for ‘WINNER’ is ‘24 10 15 15 6 19’.
While, Decoding is the reverse process of coding. It involves converting the encoded message
back to its original form using the same pattern, rule, or system that was used to encode it.

Example 6: If in a language BROTHER is coded as 5708367, SISTER is coded as 919867, what is the
code for HOBSTERS?

Solution: Since it is given that BROTHER is coded as 5708367 and SISTER is coded as 919867. Thus,

B R O T H E R Quick Check

5 7 0 8 3 6 7 Decode the numbers using the
place value of alphabets and
S I S T E R find the word: 2 5 8 1 16 16 25
and
9 1 9 8 6 7
Maths Talk
After observing the codes, we get that code for H is 3, for O is 0, Explore the Internet
for B is 5, for S is 9, for T is 8, for E is 6, for R is 7, and for I is 1. and discuss how the pin code of

So, code for HOBSTERS is 30598679. a place is decided.

343 Playing With Numbers