Number Play Class 7 - Ganita Prakash
Master Number Play Class 7 - Ganita Prakash with comprehensive NCERT Solutions, Practice Questions, MCQs, Sample Papers, Case Based Questions, and Video lessons.
NCERT Solutions
Number Play Class 7 - Ganita Prakash – NCERT Solutions
Each question below opens its complete step-by-step Teachoo solution.
Figure it out - Page 131
3 questionsQuestion 1
(a)
Using your understanding of the pictorial representation of odd and even numbers, find out the parity of the following sums:
(a) Sum of 2 even numbers and 2 odd numbers (e.g., even + even + odd + odd)
Now,
(Even + Even) + (Odd + Odd)
= Even + Even
= Even
Question 1 (b)
Using your understanding of the pictorial representation of odd and even numbers, find out the parity of the following sums:
(b) Sum of 2 odd numbers and 3 even numbers
Now,
(Odd + Odd) + (Even + Even) + Even
= Even + Even + Even
= (Even + Even) + Even
= Even + Even
= Even
Question 1 (c)
Using your understanding of the pictorial representation of odd and even numbers, find out the parity of the following sums:
(c) Sum of 5 even numbers
Now,
(Even + Even) + (Even + Even) + Even
= Even + Even + Even
= (Even + Even) + Even
= Even + Even
= Even
Question 1 (d)
Using your understanding of the pictorial representation of odd and even numbers, find out the parity of the following sums:
(d) Sum of 8 odd numbers
Now,
(Odd + Odd) + (Odd + Odd) + (Odd + Odd) + (Odd + Odd)
= Even + Even + Even + Even
= (Even + Even) + (Even + Even)
= Even + Even
= Even
Question 2
Lakpa has an odd number of ₹1 coins, an odd number of ₹5 coins and an even number of ₹10 coins in his piggy bank. He calculated the total and got ₹205. Did he make a mistake? If he did, explain why. If he didn’t, how many coins of each type could he have?
Let’s solve this one by one
Question 3
We know that:
(a) even + even = even
(b) odd + odd = even
(c) even + odd = odd
Similarly, find out the parity for the scenarios below:
(d) even – even = ___________________
(e) odd – odd = ___________________
(f) even – odd = ___________________
(g) odd – even = ___________________
Okay let’s do this
(d) even - even = even
(Example: 10 - 4 = 6)
Figure it out - Page 136
5 questionsQuestion 1
How many different magic squares can be made using the numbers 1 – 9?
Our rules for making magic squares are
Middle position is 5
Four corner positions must be filled by even numbers (2, 4, 6, 8)
Four middle positions must be filled by odd numbers (1, 3, 7, 9)
Question 2
Create a magic square using the numbers 2 – 10. What strategy would you use for this? Compare it with the magic squares made using 1 – 9.
We can use the same logic as the 1-9 square, or we can use a clever shortcut
Question 3
Take a magic square, and
(a) increase each number by 1
(b) double each number
In each case, is the resulting grid also a magic square? How do the magic sums change in each case?
Yes, the resulting grid is also a magic square in both cases.
The magic property is preserved when you perform the same linear operation on every number.
Question 4
What other operations can be performed on a magic square to yield another magic square?
Besides adding a constant or multiplying by a constant, you can also:
Subtract a constant from every number.
Divide every number by a constant (if they are all divisible).
Rotate the square by 90°, 180°, or 270°.
Reflect (flip) the square horizontally or vertically.
Question 5
Discuss ways of creating a magic square using any set of 9 consecutive numbers (like 2 – 10, 3 – 11, 9 – 17, etc.).
The easiest way is to use the transformation method.
Start with the standard 1-9 magic square.
Identify the first number of your new sequence (let's call it x).
Calculate the difference: d = x - 1.
Add this difference d to every number in the 1-9 magic square.
Figure it out - Page 143, 144
11 questionsQuestion 1
A light bulb is ON. Dorjee toggles its switch 77 times. Will the bulb be on or off? Why?
The state of the bulb depends on the parity (odd or even) of the number of times the switch is toggled.
It starts ON
After 1 toggle (odd), it's OFF
After 2 toggles (even), it's ON
After 3 toggles (odd), it's OFF
Question 2
Liswini has a large old encyclopedia. When she opened it, several loose pages fell out of it. She counted 50 sheets in total, each printed on both sides. Can the sum of the page numbers of the loose sheets be 6000? Why or why not?
Let’s try to figure out how to go about it
Each loose sheet has two pages with consecutive numbers (e.g., page 5 and page 6)
The sum of any two consecutive numbers is always even + odd = odd
Liswini has 50 sheets, so the total sum is the sum of 50 odd numbers.
Sum of 2 odd numbers is even, sum of 3 odd numbers is odd
Thus, we can say sum of 50 odd numbers would be even
Question 3
Here is a 2 × 3 grid. For each row and column, the parity of the sum is written in the circle; ‘e’ for even and ‘o’ for odd. Fill the 6 boxes with 3 odd numbers (‘o’) and 3 even numbers (‘e’) to satisfy the parity of the row and column sums.
Let’s name Rows and Columns and figure this out
Now,
Sum of Column 1 is even – so it could be e + e or o + o
Let’s take o + o
Sum of Column 2 is even – so it could be e + e or o + o
Let’s take e + e in this case
Sum of Column 3 is odd – so its either e + o or o + e
Since Row 1 is odd – o + (e + e) = o + e = o
So, let top right be odd
Hence, bottom right would be even
So, Sum of Row 2 – o + (e + 0) = o + o = e
Question 4
Make a 3 × 3 magic square with 0 as the magic sum. All numbers can not be zero. Use negative numbers, as needed.
We can do this with a Generalised magic square
Question 5
(a)
Fill in the following blanks with ‘odd’ or ‘even’:
(a) Sum of an odd number of even numbers is ______
Let’s do this with example
Sum of 3 even numbers
Even + Even + Even
= Even + (Even + Even)
= Even + Even
= Even
Question 6
(Method 1)
What is the parity of the sum of the numbers from 1 to 100?
In the numbers from 1 to 100, there are 50 odd numbers and 50 even numbers.
The sum of the 50 odd numbers is even (an even number of odds).
The sum of the 50 even numbers is even.
Question 7
Two consecutive numbers in the Virahāṅka sequence are 987 and 1597. What are the next 2 numbers in the sequence? What are the previous 2 numbers in the sequence?
The rule for the Virahāńka sequence is that each new term is the sum of the two previous terms.
Question 8
Angaan wants to climb an 8-step staircase. His playful rule is that he can take either 1 step or 2 steps at a time. For example, one of his paths is 1, 2, 2, 1, 2. In how many different ways can he reach the top?
We can make a table for this
Steps to climb All possible ways Number of ways
1 (1) 1
2 (1+1), (2) 2
3
3
4
5
5 combine step 4 &
8
6
13
7
21
8
34This problem is a real-world example of the Virahāńka sequence.
The number of ways to climb n steps by taking 1 or 2 steps at a time is the nth term of the sequence
1, 2, 3, 5, 8, ....
Question 9
What is the parity of the 20th term of the Virahāṅka sequence?
Now, our Virahāṅka–Fibonacci sequence is
1, 2, 3, 5, 8, 13, 21, 34, …
Question 10
(a)
Identify the statements that are true.
(a) The expression 4m – 1 always gives odd numbers
Here,
4m is always even
1 is always odd
Question 11
Solve this cryptarithm:
Here,
Adding two 2-digit numbers gives 3 digit number
Why Learn This With Teachoo?
Number Play is Chapter 6 of NCERT Class 7 Ganita Prakash Part 1. It explores patterns, parity, grids, magic squares, historical number sequences and digit puzzles. Rather than presenting numbers only as objects for calculation, the chapter invites students to experiment, make conjectures and explain why a pattern works. Teachoo organises these investigations concept-wise and provides step-by-step support for the chapter’s Figure it out questions.
What is Number Play about?
The chapter begins with the idea that numbers can tell us things. Through Supercells and grid-based activities, students observe how a number’s position and relationship with neighbouring numbers can create a rule. Such tasks strengthen attention to structure and encourage multiple strategies.
A major idea is parity, which describes whether an integer is even or odd. The parity of a sum, difference or product can often be predicted without calculating its full value. For example, multiplying any integer by an even integer produces an even product. Multiplying two odd integers produces an odd product. Students use small squares in grids to investigate parity in multiplication and then extend the same reasoning to expressions.
Grid explorations lead to magic squares. In a magic square, numbers are arranged so that specified rows, columns and diagonals have the same sum. Students study 3 × 3 magic squares, generalise their construction or properties and encounter the first known 4 × 4 magic square. The historical and cultural discussion shows that mathematical recreation has a long tradition across societies.
Virahāṅka Fibonacci numbers introduce a famous recursive pattern in which later terms are formed from earlier terms. This links Indian mathematical history with sequence reasoning. Digits in Disguise presents puzzles where digits or symbols must satisfy conditions, requiring systematic testing and logical elimination.
The Figure it out questions on pages 131, 136 and 143–144 combine parity, grid patterns, magic squares and number puzzles. More than one approach may be possible, so a complete answer should include an explanation.
Topics covered on Teachoo
The chapter page includes:
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Numbers Can Tell Us Things and Supercells;
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parity of integers;
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small squares in grids and parity in multiplication;
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parity of expressions;
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explorations in number grids;
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magic squares;
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generalising a 3 × 3 magic square;
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the earliest known 4 × 4 magic square;
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magic squares in history and culture;
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Virahāṅka Fibonacci numbers;
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Digits in Disguise; and
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explained Figure it out solutions.
Learning outcomes
Students should be able to predict the parity of sums, products and simple expressions, extend rules in grids, calculate and verify a magic sum and describe a recursive sequence. They should organise cases in a digit puzzle and distinguish an observed pattern from a justified rule. A strong answer includes evidence—examples, a table, a parity argument or a structural explanation—rather than an unsupported guess.
Why is this chapter important?
Number Play develops mathematical habits that routine exercises may not fully test: looking for invariants, organising cases, spotting counterexamples and generalising from evidence. These habits are valuable in algebra, computer science, combinatorics and competitive problem solving.
Parity is especially powerful because it provides a quick impossibility test. If an expected result must be odd but the given operations always produce an even number, a student can prove that the proposed situation is impossible without checking every number.
How Teachoo helps you learn
Teachoo separates each investigation into a focused topic. Students can revisit the exact concept behind a puzzle, follow a worked explanation and compare different ways of reasoning. For the best results, do not open the solution immediately. Make a table, draw the grid, test small cases and record what stays unchanged. Then use the Teachoo answer to evaluate the completeness of your explanation.
For parity questions, replace actual numbers mentally by the labels odd and even. For sequences, write several terms and state the rule connecting them. For magic squares, calculate the common sum and inspect opposite or central positions before guessing randomly.
Common mistakes to avoid
A pattern seen in two examples is not automatically a general rule. Test more cases and give a reason. Do not confuse the parity of a number with the parity of its digits; an integer’s parity is determined by its units digit. In a magic square, verify every required row, column and diagonal, not only one or two lines.
Digit puzzles should be solved systematically. Keep a record of eliminated possibilities so that the same failed case is not repeated.
Deeper reasoning and concept connections
The strongest way to learn Number Play (Ganita Prakash) is to separate three layers: the object being studied, the rule that describes it and the reason the rule works. A correct numerical result is useful, but a complete mathematical answer also explains the relationship used. Students should compare examples and non-examples, change one condition at a time and observe whether the conclusion still holds.
This chapter is part of a longer progression. Its vocabulary and representations will appear again in algebra, geometry, data, measurement or higher problem-solving. Build links deliberately: translate pictures into statements, statements into operations and operations back into a sensible interpretation. If the final result cannot be explained in ordinary language, the method has probably been followed mechanically rather than understood.
How to solve unfamiliar and competency-based questions
When a question looks new, do not search memory for an identical example. Classify it. Decide whether it asks for recognition, calculation, representation, comparison, explanation or proof. Write the relevant definition or property first. Next, organise the data and select the shortest valid method. This converts an unfamiliar surface story into a familiar mathematical structure.
Use estimation and special cases as quality checks. Test zero, one, equal values, endpoints or a simple symmetric figure whenever they are permitted. A result that violates the diagram, scale, sign, unit or expected range is a signal to recheck the setup. In multi-part cases, carry forward only verified results so one early error does not silently contaminate every later answer.
What complete mastery looks like
For Number Play (Ganita Prakash), a student should be able to define the central ideas in simple language, recognise them in different representations, solve routine questions accurately and explain the method used. They should also be able to correct a flawed solution, create an example satisfying given conditions and combine two ideas from the chapter in one problem. A reliable mastery test is to solve one direct question, one application question and one reasoning question without looking at notes, then explain all three aloud or in writing.
Keep a compact error log with four labels: concept, interpretation, calculation and presentation. Reattempt each error after a gap instead of rereading the answer immediately. Improvement comes from correcting the decision that caused the mistake, not from repeating questions whose method is already known.
Additional frequently asked questions
What should a student know before starting Number Play (Ganita Prakash)?
Revise the definitions, number operations, diagrams or notation used at the beginning of the chapter. The prerequisite list should be short: if an earlier skill blocks progress, repair that skill with two or three focused questions and return to the chapter.
How can a student check an answer in Number Play (Ganita Prakash)?
Use an independent check whenever possible: substitute the result, reverse the operation, estimate its size, compare it with the figure, test a simpler case or solve using another representation. A check should examine the mathematical condition, not merely repeat the same arithmetic.
How many questions are enough for strong preparation?
There is no fixed number. Stop counting questions and track coverage: every concept, every standard method, at least one mixed problem, one competency-based problem and every previously incorrect type should be solved independently. Ten varied, analysed questions are more valuable than fifty copied solutions.
How should Teachoo solutions be used without becoming dependent on them?
Attempt the question first and mark the exact step where progress stops. Read only enough of the solution to repair that step, close it and restart the question. Finally, solve a similar problem without help. This turns a solution into feedback rather than a substitute for thinking.
Frequently asked questions
What is parity in Class 7 Maths?
Parity is the classification of integers as even or odd and the study of how that property behaves under operations.
What is a magic square?
It is a square arrangement of numbers in which specified rows, columns and diagonals have an equal sum, called the magic sum.
Are Virahāṅka numbers related to Fibonacci numbers?
Yes. The chapter studies the recursive sequence associated with Virahāṅka and commonly connected with the Fibonacci pattern.
Approach Number Play as a mathematical laboratory. Explore first, organise your observations and then convert the pattern into a convincing explanation.