NCERT Book Class 7 Mathematics (Part II) Chapter 2 Operations with Integers

2 OPERATIONS
WITH INTEGERS

2.1 A Quick Recap of Integers
Rakesh’s Puzzle: A Number Game

Rakesh gives you a challenge.
“I have thought of two numbers”, he says.
“Their sum is 25, and their difference is 11.”

Can you tell me the two numbers?
You don’t need to use any formulas. Just try different pairs of numbers
and then check:
1. Do the two numbers add up to 25?
2. Is the difference between them 11?
(Remember: the difference means first number – second number.)
Write your guesses like this:

First Number Second Number Sum Difference
10 15 25 –5
20 5 25 15
19 6 25 13
18 7 25 11

Did you find the right pair?

Now that you’ve found the correct pair, Rakesh gives you a second
challenge:
“Think of two numbers whose sum is 25, but their difference is –11.”
Use the same method. Try different pairs of numbers and fill in the
table again. You will notice that if you swap the numbers from the first

Chapter-2.indd 24 10/9/2025 2:27:38 PM