Q: What if the game was played till 900? How would your answers change?

Number of multiples of 3 from 1 till 900 = $\frac{900}{3}$ = 300Number of multiples of 5 from 1 till 900 = $\frac{900}{5}$ = 180Number of multiples of 15 from 1 till 900 = $\frac{900}{15}$ = 60

Question 1

At what number is ‘idli-vada’ said for the 10th time?

Accepted Answer

To determine the 10th occurrence of “idli- vada”; we need to identify the numbers that are multiples of both 3 and 5.The numbers for which “idli-vada” is said are the multiples of 15.This sequence is: 15,30,45,60, 75,90, 105, 120,135,150,…Thus, the 10th number for which players should say “idli-vada” is 150.

Question 2

If the game is played for the numbers from 1 to 90, find out: (Medium)
(a) How many times would the children say ‘idli’ (including the times they say ‘idli-vada’)?
(b) How many times would the children say ‘vada’ (including the times they say ‘idli-vada’)?
(c) How many times would the children say ‘idli-vada’?

Accepted Answer

(a) 30 times would the children say ‘idli’ (including the times they say ‘idli-vada’) because, between 1 to 90, there are 30 numbers that are multiple of 3.3, 6, 9, 12, 15, 18, 21,……..(b) 18 times would the children say ‘vada’ (including the times they say ‘idli-vada’) because, between 1 to 90, there are 18 numbers which are multiple of 5.5, 10, 15, 20, 25, 30,……….(c) 6 times would the children say ‘idli-vada’.15, 30, 45, 60, 75, 90.

Question 3

What if the game was played till 900? How would your answers change?

Accepted Answer

Number of multiples of 3 from 1 till 900 = $\frac{900}{3}$ = 300Number of multiples of 5 from 1 till 900 = $\frac{900}{5}$ = 180Number of multiples of 15 from 1 till 900 = $\frac{900}{15}$ = 60

Question 4

Is this figure somehow related to the ‘idli- vada’ game? (Hint: Imagine playing the game till 30. Draw the figure if the game is played till 60.)

Accepted Answer

Yes, this figure is related to the ‘idli-vada’ game. Figure below for game played till 60.Intext Questions

Source: This question is from Prime Time, Mathematics &mdash; Class 6, CBSE Board.
Key Concepts CoveredThis question tests your understanding of the following concepts from the chapter Prime Time: Figure, Somehow, Related, Idli, Vada, Game. These are fundamental topics in Mathematics that students are expected to master as part of the CBSE Class 6 curriculum.A thorough understanding of these concepts will help you answer similar questions confidently in your CBSE examinations. These topics are frequently tested in both objective and subjective sections of Mathematics papers. We recommend revising the relevant section of your textbook alongside practising these solved examples to build a strong foundation.
How to Approach This QuestionRead the question carefully and identify what is being asked. Break down complex questions into smaller parts. Use the terminology and concepts discussed in this chapter. Structure your answer logically — begin with a definition or key statement, then provide supporting details. Review your answer to ensure it addresses all parts of the question completely.
Key Points to RememberAlways show your working steps clearly.
Verify your answer by substituting values back into the equation.
Practice similar problems from the textbook exercises.
Memorise important formulae and their conditions of applicability.
Related Questions from Prime TimeQ1: At what number is ‘idli-vada’ said for the 10th time?
Q10: Who am I? (a) I am a number less than 40. One of my factors is 7. The sum of my digits is 8. (b) I...
Q12: Find the common factors of: (a) 20 and 28 (b) 35 and 50 (c) 4, 8 and 12 (d) 5, 15 and 25
Q13: Find any three numbers that are multiples of 25 but not multiples of 50.
Q14: Anshu and his friends play the ‘idli-vada’ game with two numbers, which are both smaller than 10....
Practice more questions from Prime Time &mdash; Mathematics, Class 6 CBSE

Question 5

Which of the following could be the other number:
2,3, 5, 8, 10? (Page 109)

Accepted Answer

As one of the numbers was 4. Among the given numbers, every multiple of 8 is also a multiple of 4. So, the other number is 8.

Source: This question is from Prime Time, Mathematics &mdash; Class 6, CBSE Board.
Key Concepts CoveredThis question tests your understanding of the following concepts from the chapter Prime Time: Number, Page, Prime Time, Mathematics. These are fundamental topics in Mathematics that students are expected to master as part of the CBSE Class 6 curriculum.A thorough understanding of these concepts will help you answer similar questions confidently in your CBSE examinations. These topics are frequently tested in both objective and subjective sections of Mathematics papers. We recommend revising the relevant section of your textbook alongside practising these solved examples to build a strong foundation.
How to Approach This QuestionRead the question carefully and identify what is being asked. Break down complex questions into smaller parts. Use the terminology and concepts discussed in this chapter. Structure your answer logically — begin with a definition or key statement, then provide supporting details. Review your answer to ensure it addresses all parts of the question completely.
Key Points to RememberAlways show your working steps clearly.
Verify your answer by substituting values back into the equation.
Practice similar problems from the textbook exercises.
Memorise important formulae and their conditions of applicability.
Related Questions from Prime TimeQ1: At what number is ‘idli-vada’ said for the 10th time?
Q10: Who am I? (a) I am a number less than 40. One of my factors is 7. The sum of my digits is 8. (b) I...
Q12: Find the common factors of: (a) 20 and 28 (b) 35 and 50 (c) 4, 8 and 12 (d) 5, 15 and 25
Q13: Find any three numbers that are multiples of 25 but not multiples of 50.
Q14: Anshu and his friends play the ‘idli-vada’ game with two numbers, which are both smaller than 10....
Practice more questions from Prime Time &mdash; Mathematics, Class 6 CBSE

Question 6

What jump size can reach both 15 and 30? There are multiple jump sizes possible. Try to find them all. (Page 110)

Accepted Answer

Factors of 15 are 1, 3, 5 and 15Factors of 30 are 1, 2, 3, 5, 6, 10, 15 and 30The jump size that reach both 15 and 30 are 1, 3, 5 and 15, the common factors of 15 and 30.

Source: This question is from Prime Time, Mathematics &mdash; Class 6, CBSE Board.
Key Concepts CoveredThis question tests your understanding of the following concepts from the chapter Prime Time: Jump, Size, Reach, There, Multiple, Sizes. These are fundamental topics in Mathematics that students are expected to master as part of the CBSE Class 6 curriculum.A thorough understanding of these concepts will help you answer similar questions confidently in your CBSE examinations. These topics are frequently tested in both objective and subjective sections of Mathematics papers. We recommend revising the relevant section of your textbook alongside practising these solved examples to build a strong foundation.
How to Approach This QuestionRead the question carefully and identify what is being asked. Break down complex questions into smaller parts. Use the terminology and concepts discussed in this chapter. Structure your answer logically — begin with a definition or key statement, then provide supporting details. Review your answer to ensure it addresses all parts of the question completely.
Key Points to RememberAlways show your working steps clearly.
Verify your answer by substituting values back into the equation.
Practice similar problems from the textbook exercises.
Memorise important formulae and their conditions of applicability.
Related Questions from Prime TimeQ1: At what number is ‘idli-vada’ said for the 10th time?
Q10: Who am I? (a) I am a number less than 40. One of my factors is 7. The sum of my digits is 8. (b) I...
Q12: Find the common factors of: (a) 20 and 28 (b) 35 and 50 (c) 4, 8 and 12 (d) 5, 15 and 25
Q13: Find any three numbers that are multiples of 25 but not multiples of 50.
Q14: Anshu and his friends play the ‘idli-vada’ game with two numbers, which are both smaller than 10....
Practice more questions from Prime Time &mdash; Mathematics, Class 6 CBSE

Question 7

Look at the table below. What do you notice?
In the table,
1. Is there anything common among the shaded numbers?

Accepted Answer

The shaded numbers are the multiples of 3 starting from 33.2. Is there anything common among the circled numbers?Solution:The circled numbers are the multiples of 4 starting from 32.3. Which numbers are both shaded and circled? What are these numbers called?Solution:Numbers 36,48 and 60 are both shaded and circled. These numbers are called common multiples of 3 and 4.5.1 Common Multiples and Common Factors Figure it Out (Page No. 110 – 111)

Question 8

Find all multiples of 40 that lie between 310 and 410.

Accepted Answer

The numbers which are multiple of 40 lying between 310 and 410 are 320, 360, and 400.

Source: This question is from Prime Time, Mathematics &mdash; Class 6, CBSE Board.
Key Concepts CoveredThis question tests your understanding of the following concepts from the chapter Prime Time: Multiples, Lie, Prime Time, Mathematics. These are fundamental topics in Mathematics that students are expected to master as part of the CBSE Class 6 curriculum.A thorough understanding of these concepts will help you answer similar questions confidently in your CBSE examinations. These topics are frequently tested in both objective and subjective sections of Mathematics papers. We recommend revising the relevant section of your textbook alongside practising these solved examples to build a strong foundation.
How to Approach This QuestionRead the question carefully and identify what is being asked. Break down complex questions into smaller parts. Use the terminology and concepts discussed in this chapter. Structure your answer logically — begin with a definition or key statement, then provide supporting details. Review your answer to ensure it addresses all parts of the question completely.
Key Points to RememberAlways show your working steps clearly.
Verify your answer by substituting values back into the equation.
Practice similar problems from the textbook exercises.
Memorise important formulae and their conditions of applicability.
Related Questions from Prime TimeQ1: At what number is ‘idli-vada’ said for the 10th time?
Q10: Who am I? (a) I am a number less than 40. One of my factors is 7. The sum of my digits is 8. (b) I...
Q12: Find the common factors of: (a) 20 and 28 (b) 35 and 50 (c) 4, 8 and 12 (d) 5, 15 and 25
Q13: Find any three numbers that are multiples of 25 but not multiples of 50.
Q14: Anshu and his friends play the ‘idli-vada’ game with two numbers, which are both smaller than 10....
Practice more questions from Prime Time &mdash; Mathematics, Class 6 CBSE

Question 9

Who am I?
(a) I am a number less than 40. One of my factors is 7. The sum of my digits is 8.
(b) I am a number less than 100. Two of my factors are 3 and 5. One of my digits is 1 more than the other.

Accepted Answer

(a) 35 is a number less than 40. One of the factors is 7 and the sum of the digits is 8.(b) If the factors are 3 and 5 it has to be a multiple of 15 which are 15, 30, 45, 60, 75, and 90.By the given condition of the digit is 1 more than the other is only 45.So, 45 is a number that follows all the conditions.

Question 10

A number for which the sum of all its factors is equal to twice the number is called a perfect number. The number 28 is a perfect number. Its factors are 1, 2, 4, 7, 14 and 28. Their sum is 56 which is twice 28. Find a perfect number between 1 and 10.

Accepted Answer

Factors of 6 are 1,2 and 3.⇒ 1 + 2 + 3 + 6 = 12Since, 12 = 2 × 6∴ Sum of factors is equal to twice the number.Thus, 6 is a perfect number between 1 and 10.

Source: This question is from Prime Time, Mathematics &mdash; Class 6, CBSE Board.
Key Concepts CoveredThis question tests your understanding of the following concepts from the chapter Prime Time: Number, Sum, Factors, Equal, Twice, Perfect. These are fundamental topics in Mathematics that students are expected to master as part of the CBSE Class 6 curriculum.A thorough understanding of these concepts will help you answer similar questions confidently in your CBSE examinations. These topics are frequently tested in both objective and subjective sections of Mathematics papers. We recommend revising the relevant section of your textbook alongside practising these solved examples to build a strong foundation.
How to Approach This QuestionRead the question carefully and identify what is being asked. Break down complex questions into smaller parts. Use the terminology and concepts discussed in this chapter. Structure your answer logically — begin with a definition or key statement, then provide supporting details. Review your answer to ensure it addresses all parts of the question completely.
Key Points to RememberAlways show your working steps clearly.
Verify your answer by substituting values back into the equation.
Practice similar problems from the textbook exercises.
Memorise important formulae and their conditions of applicability.
Related Questions from Prime TimeQ1: At what number is ‘idli-vada’ said for the 10th time?
Q10: Who am I? (a) I am a number less than 40. One of my factors is 7. The sum of my digits is 8. (b) I...
Q12: Find the common factors of: (a) 20 and 28 (b) 35 and 50 (c) 4, 8 and 12 (d) 5, 15 and 25
Q13: Find any three numbers that are multiples of 25 but not multiples of 50.
Q14: Anshu and his friends play the ‘idli-vada’ game with two numbers, which are both smaller than 10....
Practice more questions from Prime Time &mdash; Mathematics, Class 6 CBSE

Question 11

Find the common factors of:
(a) 20 and 28
(b) 35 and 50
(c) 4, 8 and 12
(d) 5, 15 and 25

Accepted Answer

(a) Factors of 20 are 1,2,4, 5, 10 and 20.Factors of 28 are 1, 2,4, 7, 14 and 28.Common factors of 20 and 28 are 1, 2 and 4.(b) Factors of 35 are 1, 5, 7 and 35.Factors of 50 are 1, 2, 5, 10, 25 and 50.Common factors of 35 and 50 are 1 and 5.(c) Factors of 4 are 1, 2 and 4.Factors of 8 are 1, 2,4 and 8.Factors of 12 are 1,2, 3,4,6 and 12.Common factors of 4,8 and 12 are 1,2 and 4.(d) Factors of 5 are 1 and 5.Factors of 15 are 1, 3, 5 and 15.Factors of 25 are 1, 5 and 25.Common factors of 5,15 and 25 are 1 and 5.

Question 12

Find any three numbers that are multiples of 25 but not multiples of 50.

Accepted Answer

Multiples of 25 are: 25, 50, 75, 100, 125, 150, 175, …Multiples of 50 are: 50, 100, 150, 200, 250, …∴ The numbers that are multiples of 25 but not multiples of 50 are 25, 75, 125, 175,…

Question 13

Anshu and his friends play the ‘idli-vada’ game with two numbers, which are both smaller than 10. The first time anybody says ‘idli-vada’ is after the number 50. What could the two numbers be which are assigned ‘idli’ and ‘vada’?

Accepted Answer

The pair of numbers smaller than 10 with first common multiple greater than 50 are (7, 8), (8, 9) and (7, 9).For (7, 8):If 7, 14, 21, 28, 35, …, 49, 56, 63, … are said ‘idli’.And 8, 16, 24, 32, …, 48, 56, 64, … are said ‘vada’.Then 56 is the first number (first common multiple of 7 and 8) greater than 50 which would be said ‘idli-vada’.For (8, 9):If 8, 16, 24, 32, …, 48, 56, 64, 72, … are said ‘idli’.And 9, 18, 27, 36, …, 54, 63, 72, … are said ‘vada’.Then 72 is the first number (first common multiple of 8 and 9) greater than 50 which would be said ‘idli-vada’.For (7, 9):If 7, 14, 21, 28, …, 49, 56, 63, 70, … are said ‘idli’.And 9, 18, 27, 36, …, 54, 63, 72, … are said ‘vada’.Then 63 is the first number (first common multiple of 7 and 9) greater than 50 which would be said ‘idli-vada’.

Question 14

In the treasure hunting game, Grumpy has kept treasures on 28 and 70. What jump sizes will land on both the numbers?

Accepted Answer

In the treasure hunting game, if Grumpy has kept treasures on 28 and 70, then the common factor of 28 and 70 will be the jump sizes to land on both the numbers.Therefore,Factors of 28 are: 1, 2, 4, 7, 14, and 28.Factors of 70 are: 1, 2, 5, 7, 10, 14, 35 and 70.The common factors of 28 and 70 are: 1, 2, 7, and 14. Thus, the possible jump sizes to land on both the numbers will be 1, 2, 7, and 14.

Question 15

In the diagram below, Guna has erased all the numbers except the common multiples. Find out what those numbers could be and fill in the missing numbers in the empty regions.

Accepted Answer

Multiples of 6 Multiples of 8Here 6 could also be replaced by 3.As 24, 48, 72, are also common multiples of 3 and 8.

Source: This question is from Prime Time, Mathematics &mdash; Class 6, CBSE Board.
Key Concepts CoveredThis question tests your understanding of the following concepts from the chapter Prime Time: Guna, Erased, Numbers, Except, Common, Multiples. These are fundamental topics in Mathematics that students are expected to master as part of the CBSE Class 6 curriculum.A thorough understanding of these concepts will help you answer similar questions confidently in your CBSE examinations. These topics are frequently tested in both objective and subjective sections of Mathematics papers. We recommend revising the relevant section of your textbook alongside practising these solved examples to build a strong foundation.
How to Approach This QuestionRead the question carefully and identify what is being asked. Break down complex questions into smaller parts. Use the terminology and concepts discussed in this chapter. Structure your answer logically — begin with a definition or key statement, then provide supporting details. Review your answer to ensure it addresses all parts of the question completely.
Key Points to RememberAlways show your working steps clearly.
Verify your answer by substituting values back into the equation.
Practice similar problems from the textbook exercises.
Memorise important formulae and their conditions of applicability.
Related Questions from Prime TimeQ1: At what number is ‘idli-vada’ said for the 10th time?
Q10: Who am I? (a) I am a number less than 40. One of my factors is 7. The sum of my digits is 8. (b) I...
Q12: Find the common factors of: (a) 20 and 28 (b) 35 and 50 (c) 4, 8 and 12 (d) 5, 15 and 25
Q13: Find any three numbers that are multiples of 25 but not multiples of 50.
Q14: Anshu and his friends play the ‘idli-vada’ game with two numbers, which are both smaller than 10....
Practice more questions from Prime Time &mdash; Mathematics, Class 6 CBSE

Question 16

Find the smallest number that is a multiple of all the numbers from 1 to 10 except for 7.

Accepted Answer

To find smallest number that is a multiple of all the numbers between 1 and 10 (both inclusive), let us first find the LCM of all the numbers between 1 and 10 except 7.Here, 1 = 12 = 23 = 34 = 2 × 25 = 56 = 2 × 38 = 2 × 2 × 29 = 3 × 310 = 2 × 5∴ LCM = Product of the highest power of the prime factors including other factors= 2 × 2 × 2 × 3 × 3 × 5= 360Hence, the smallest number that is a multiple of all the numbers from 1 to 10 except for 7 is 360.

Question 17

Find the smallest number that is a multiple of all the numbers from 1 to 10.

Accepted Answer

The smallest number that is a multiple of all the numbers from 1 to 10 will be least common multiples of that numbers.2 × 2 × 3 × 5 × 7 × 2 × 3 = 2520Thus, the smallest number that is a multiple of all the numbers from 1 to 10 will be 2520.InText Questions

Question 18

How many prime numbers are there from 21 to 30? How many composite numbers are there from 21 to 30? (Page 113)

Accepted Answer

There are 2 prime numbers, (i.e., 23,29) and 8 composite numbers (i.e., 21,22, 24, 25, 26, 27, 28 and 30) from 21 to 30.5.2 Prime Numbers Figure it Out (Page No. 114 – 115)

Source: This question is from Prime Time, Mathematics &mdash; Class 6, CBSE Board.
Key Concepts CoveredThis question tests your understanding of the following concepts from the chapter Prime Time: Prime, Numbers, There, Composite, Page, Prime Time. These are fundamental topics in Mathematics that students are expected to master as part of the CBSE Class 6 curriculum.A thorough understanding of these concepts will help you answer similar questions confidently in your CBSE examinations. These topics are frequently tested in both objective and subjective sections of Mathematics papers. We recommend revising the relevant section of your textbook alongside practising these solved examples to build a strong foundation.
How to Approach This QuestionRead the question carefully and identify what is being asked. Break down complex questions into smaller parts. Use the terminology and concepts discussed in this chapter. Structure your answer logically — begin with a definition or key statement, then provide supporting details. Review your answer to ensure it addresses all parts of the question completely.
Key Points to RememberAlways show your working steps clearly.
Verify your answer by substituting values back into the equation.
Practice similar problems from the textbook exercises.
Memorise important formulae and their conditions of applicability.
Related Questions from Prime TimeQ1: At what number is ‘idli-vada’ said for the 10th time?
Q10: Who am I? (a) I am a number less than 40. One of my factors is 7. The sum of my digits is 8. (b) I...
Q12: Find the common factors of: (a) 20 and 28 (b) 35 and 50 (c) 4, 8 and 12 (d) 5, 15 and 25
Q13: Find any three numbers that are multiples of 25 but not multiples of 50.
Q14: Anshu and his friends play the ‘idli-vada’ game with two numbers, which are both smaller than 10....
Practice more questions from Prime Time &mdash; Mathematics, Class 6 CBSE

Question 19

We see that 2 is a prime and also an even number. Is there any other even prime?

Accepted Answer

No, there is no other prime number. 2 is also the smallest prime number.

Source: This question is from Prime Time, Mathematics &mdash; Class 6, CBSE Board.
Key Concepts CoveredThis question tests your understanding of the following concepts from the chapter Prime Time: See, Prime, Number, There, Prime Time, Mathematics. These are fundamental topics in Mathematics that students are expected to master as part of the CBSE Class 6 curriculum.A thorough understanding of these concepts will help you answer similar questions confidently in your CBSE examinations. These topics are frequently tested in both objective and subjective sections of Mathematics papers. We recommend revising the relevant section of your textbook alongside practising these solved examples to build a strong foundation.
How to Approach This QuestionRead the question carefully and identify what is being asked. Break down complex questions into smaller parts. Use the terminology and concepts discussed in this chapter. Structure your answer logically — begin with a definition or key statement, then provide supporting details. Review your answer to ensure it addresses all parts of the question completely.
Key Points to RememberAlways show your working steps clearly.
Verify your answer by substituting values back into the equation.
Practice similar problems from the textbook exercises.
Memorise important formulae and their conditions of applicability.
Related Questions from Prime TimeQ1: At what number is ‘idli-vada’ said for the 10th time?
Q10: Who am I? (a) I am a number less than 40. One of my factors is 7. The sum of my digits is 8. (b) I...
Q12: Find the common factors of: (a) 20 and 28 (b) 35 and 50 (c) 4, 8 and 12 (d) 5, 15 and 25
Q13: Find any three numbers that are multiples of 25 but not multiples of 50.
Q14: Anshu and his friends play the ‘idli-vada’ game with two numbers, which are both smaller than 10....
Practice more questions from Prime Time &mdash; Mathematics, Class 6 CBSE

Question 20

Look at the list of primes to 100. What is the smallest difference between two successive primes? What is the largest difference?

Accepted Answer

The smallest difference between two successive primes is 1 = 3 – 2The largest difference between two successive primes is 8 = 97 – 89.

Source: This question is from Prime Time, Mathematics &mdash; Class 6, CBSE Board.
Key Concepts CoveredThis question tests your understanding of the following concepts from the chapter Prime Time: Look, Primes, Smallest, Successive, Largest, Prime Time. These are fundamental topics in Mathematics that students are expected to master as part of the CBSE Class 6 curriculum.A thorough understanding of these concepts will help you answer similar questions confidently in your CBSE examinations. These topics are frequently tested in both objective and subjective sections of Mathematics papers. We recommend revising the relevant section of your textbook alongside practising these solved examples to build a strong foundation.
How to Approach This QuestionRead the question carefully and identify what is being asked. Break down complex questions into smaller parts. Use the terminology and concepts discussed in this chapter. Structure your answer logically — begin with a definition or key statement, then provide supporting details. Review your answer to ensure it addresses all parts of the question completely.
Key Points to RememberAlways show your working steps clearly.
Verify your answer by substituting values back into the equation.
Practice similar problems from the textbook exercises.
Memorise important formulae and their conditions of applicability.
Related Questions from Prime TimeQ1: At what number is ‘idli-vada’ said for the 10th time?
Q10: Who am I? (a) I am a number less than 40. One of my factors is 7. The sum of my digits is 8. (b) I...
Q12: Find the common factors of: (a) 20 and 28 (b) 35 and 50 (c) 4, 8 and 12 (d) 5, 15 and 25
Q13: Find any three numbers that are multiples of 25 but not multiples of 50.
Q14: Anshu and his friends play the ‘idli-vada’ game with two numbers, which are both smaller than 10....
Practice more questions from Prime Time &mdash; Mathematics, Class 6 CBSE