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All questions of Number Play for Class 6 Exam

The number of whole numbers between the smallest whole number and the greatest 2-digit number is
  • a)
    98
  • b)
    88
  • c)
    99
  • d)
    100
Correct answer is option 'A'. Can you explain this answer?

Dr Manju Sen answered
The smallest whole number is 0, and the greatest 2-digit number is 99. Whole numbers between them are from 1 to 98.
Count: 99 - 0 - 1 = 98.
  • Start with 99−0:
    Subtract the smallest whole number (0) from the greatest 2-digit number (99), which gives 99.
    This step counts all whole numbers from 0 to 99, inclusive.
  • Subtract 1:
    To exclude both the smallest whole number (0) and the greatest 2-digit number (99) from the total count, we subtract 1 for 0 and another 1 for 99. Hence, we subtract 1.
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If a number 38,800 is formed using 25,000, 13,000, and two 400s, what is the missing number?
  • a)
    400
  • b)
    300
  • c)
    500
  • d)
    0
Correct answer is option 'D'. Can you explain this answer?

Surbhi Patel answered
Understanding the Problem
To find the missing number that contributes to the total of 38,800, we can break down the components provided:
- 25,000
- 13,000
- Two 400s
Calculating the Known Values
Let's sum the known numbers:
- 25,000 + 13,000 = 38,000
- Adding two 400s: 400 + 400 = 800
- Now sum these values: 38,000 + 800 = 38,800
Finding the Missing Number
To determine the missing number, we can subtract the sum of the known values from the total:
- Total: 38,800
- Known sum: 38,000 + 800 = 38,800
When we check the difference:
- 38,800 - 38,800 = 0
Conclusion: The Missing Number
The missing number that, when added to 25,000, 13,000, and two 400s, results in 38,800 is:
- 0
Thus, the correct answer is option 'D', which is 0.
This reveals that no additional number is needed to achieve the total since all components already sum up perfectly to 38,800.

How many digits are there in a 5-digit number?
  • a)
    4
  • b)
    5
  • c)
    6
  • d)
    7
Correct answer is option 'B'. Can you explain this answer?

Mehul Sharma answered
Number of Digits in a 5-Digit Number

Explanation:
A 5-digit number is a number that has 5 digits in total. Let's break down the explanation further:
  • Definition of a Digit: A digit is a symbol used to represent numbers from 0 to 9.
  • Understanding Digits in Numbers: In a multi-digit number, each place value position represents a power of 10. The rightmost digit is in the ones place, the next digit to the left is in the tens place, and so on.
  • Counting the Digits: To determine the number of digits in a 5-digit number, we simply count the total number of individual digits in the number. Since a 5-digit number has 5 places, it will have a total of 5 digits.


Therefore, the correct answer to the question "How many digits are there in a 5-digit number?" is option B) 5. A 5-digit number consists of 5 individual digits, each representing a specific place value within the number.

What is the Kaprekar constant for 4-digit numbers?
  • a)
    495
  • b)
    6174
  • c)
    8127
  • d)
    8372
Correct answer is option 'B'. Can you explain this answer?

Vp Classes answered
The Kaprekar constant for 4-digit numbers is 6174. No matter what 4-digit number you start with, if you repeat the steps of arranging digits in descending and ascending order, subtracting the smaller from the larger, you will eventually reach 6174.

When 578 is subtracted from the smallest 5-digit number, we get
  • a)
    9422
  • b)
    9432
  • c)
    9522
  • d)
    none of these
Correct answer is option 'A'. Can you explain this answer?

Mehul Sharma answered
Understanding the Problem
To solve the problem, we need to determine what happens when we subtract 578 from the smallest 5-digit number.
Smallest 5-Digit Number
- The smallest 5-digit number is 10000.
Performing the Subtraction
- We will subtract 578 from 10000:
10000 - 578
Calculating the Result
- Let's perform the calculation step by step:
- Start with 10000.
- Subtract 500: 10000 - 500 = 9500.
- Subtract 70: 9500 - 70 = 9430.
- Finally, subtract 8: 9430 - 8 = 9422.
Conclusion
- Therefore, when we subtract 578 from the smallest 5-digit number (10000), we get 9422.
Options Review
- Now let's review the options given:
- a) 9422 (Correct)
- b) 9432
- c) 9522
- d) none of these
- The correct answer is option 'A': 9422.
Final Insight
- This problem illustrates basic subtraction and the significance of understanding place values, especially when dealing with large numbers like 5-digit figures.

The whole number which does not have a predecessor in the whole number system is
  • a)
    0
  • b)
    1
  • c)
    2
  • d)
    none of these
Correct answer is option 'A'. Can you explain this answer?

Shubham Gupta answered
Understanding Whole Numbers
Whole numbers are the set of numbers that include all the natural numbers along with zero. The set of whole numbers is represented as {0, 1, 2, 3, ...} and so on.
What is a Predecessor?
A predecessor is a number that comes just before another number in a sequence. For instance:
  • The predecessor of 1 is 0.
  • The predecessor of 2 is 1.
  • The predecessor of 3 is 2.

Why 0 is Special?
In the context of whole numbers:
  • 0 is the smallest whole number.
  • There is no whole number that comes before 0.
  • Thus, 0 does not have a predecessor in the whole number system.

Conclusion
Since 0 is the smallest whole number and does not have a predecessor, the correct answer to the question is option 'A'.
  • 0 is unique in the whole number system.
  • It serves as the starting point for counting.

In summary, the whole number that does not have a predecessor in the whole number system is indeed 0.

Which of the following is NOT a pattern of time found on a 12-hour clock?
  • a)
    4:44
  • b)
    10:10
  • c)
    13:13
  • d)
    12:12
Correct answer is option 'C'. Can you explain this answer?

Rohini Seth answered
On a 12-hour clock, 13:13 does not exist as the hour goes only up to 12. The other times (4:44, 10:10, 12:12) are valid patterns on a 12-hour clock.

What is the largest number that can be formed using the digits 6382?
  • a)
    8632
  • b)
    8362
  • c)
    8623
  • d)
    8236
Correct answer is option 'A'. Can you explain this answer?

Rahul Kumar answered
To form the largest number, arrange the digits in descending order. The largest number formed by 6382 is 8632.

If a 5-digit palindrome has a third digit that is twice the second digit and the fourth digit that is twice the third, what is the number?
  • a)
    13531
  • b)
    24642
  • c)
    10001
  • d)
    25752
Correct answer is option 'C'. Can you explain this answer?

Nilotpal Nambiar answered
Explanation:

Given conditions:
- The number is a 5-digit palindrome.
- The third digit is twice the second digit.
- The fourth digit is twice the third digit.

Steps to find the number:
1. Let's assume the palindrome number is abcba, where a, b, c are digits.
2. Since it is a palindrome number, a = a (the first and last digits are the same).
3. The third digit is twice the second digit, so c = 2b.
4. The fourth digit is twice the third digit, so b = 2c = 4b (substitute c = 2b).
5. From step 4, we get b = 0 which is not possible as b is a digit from 1 to 9.
6. Hence, the assumption made in step 1 is incorrect.
7. Let's try another assumption where the number is abccba.
8. Using the conditions:
- a = a (first and last digits are the same)
- c = 2b (the third digit is twice the second digit)
- c = 2c = 4b (the fourth digit is twice the third digit)
9. From the above conditions, we get b = 1 and c = 2.
10. Therefore, the number is 14641.
So, the correct answer is option C) 14641.

How many times does the digit '7' appear when writing all the numbers from 1 to 100?
  • a)
    10
  • b)
    15
  • c)
    20
  • d)
    25
Correct answer is option 'C'. Can you explain this answer?

Coachify answered
The digit '7' appears in the 7th, 17th, 27th, 37th, 47th, 57th, 67th, 70-79 (10 times), and 87th, 97th, totaling 20 times.

Number of whole numbers between 38 and 68 is
  • a)
    28
  • b)
    29
  • c)
    30
  • d)
    31
Correct answer is option 'B'. Can you explain this answer?

Palak Nambiar answered
Understanding the Problem
To find the number of whole numbers between 38 and 68, we need to focus on what "between" means. This implies we should not include the endpoints, 38 and 68, themselves.
Identifying the Range
The whole numbers we are interested in are:
- Start: 39 (the first whole number after 38)
- End: 67 (the last whole number before 68)
Counting the Whole Numbers
Now, we can count the whole numbers from 39 to 67:
- The sequence of numbers is: 39, 40, 41, ..., 67.
Calculating the Count
To find how many numbers are in this range, we can use the formula:
- Count = (Last number - First number) + 1
Plugging in our values:
- Count = (67 - 39) + 1
This simplifies to:
- Count = 28 + 1 = 29
Conclusion
Thus, the total number of whole numbers between 38 and 68 is 29. Therefore, the correct answer is option 'B'.
Summary of Steps
- Identify the starting number (39) and ending number (67)
- Count the numbers in the range
- Use the formula to calculate the total
This method ensures that you accurately find the count of whole numbers in any given range.

Which of the following numbers will you arrive at after performing Kaprekar's process starting with 4176?
  • a)
    495
  • b)
    8392
  • c)
    6174
  • d)
    1764
Correct answer is option 'C'. Can you explain this answer?

Debolina Shah answered
Understanding Kaprekar's Process
Kaprekar's process involves rearranging the digits of a number to find a specific result. Let's apply this to the number 4176.
Steps of Kaprekar's Process:
1. Arrange Digits in Descending Order:
- For 4176, the digits arranged from highest to lowest are 7641.
2. Arrange Digits in Ascending Order:
- The digits arranged from lowest to highest are 1467.
3. Subtract the Two Results:
- Now we subtract the smaller number from the larger number:
- 7641 - 1467 = 6174.
Result of Kaprekar's Process:
- The result after performing Kaprekar's process on 4176 is 6174.
Conclusion:
- Repeating the process will eventually lead to the same number, 6174, known as Kaprekar's constant.
Thus, starting with 4176 and applying Kaprekar's process, the final answer is indeed option C: 6174.

How many 3-digit palindromic numbers can be created using the digits 1, 2, and 3?
  • a)
    2
  • b)
    4
  • c)
    6
  • d)
    8
Correct answer is option 'C'. Can you explain this answer?

Coachify answered
The possible 3-digit palindromes using the digits 1, 2, and 3 are 121, 131, 212, 232, 313, and 323. There are 6 such numbers.

The number of whole numbers between 22 and 54 is
  • a)
    31
  • b)
    32
  • c)
    42
  • d)
    30
Correct answer is option 'A'. Can you explain this answer?

Palak Nambiar answered
Understanding the Range
To find the number of whole numbers between 22 and 54, we first need to clarify what "between" means in this context. We are looking for whole numbers that are greater than 22 and less than 54.
Identifying Whole Numbers
The whole numbers between 22 and 54 include:
- 23
- 24
- 25
- ...
- 53
Counting the Whole Numbers
To count these numbers, we can use the formula for counting integers in a range:
1. Identify the starting point and endpoint:
- Starting point: 23 (the first whole number greater than 22)
- Endpoint: 53 (the last whole number less than 54)
2. Count the total numbers:
- The formula for counting whole numbers between two numbers is:
(Endpoint - Starting point) + 1
- Plugging in our numbers:
(53 - 23) + 1 = 30 + 1 = 31
Conclusion
Thus, the total number of whole numbers between 22 and 54 is 31. Therefore, the correct answer is option 'A'.
This approach shows how to systematically find the count of numbers in a given range, ensuring clarity and accuracy in the solution.

Which of the following numbers is a palindrome?
  • a)
    34544
  • b)
    12321
  • c)
    65457
  • d)
    78998
Correct answer is option 'B'. Can you explain this answer?

Subset Academy answered
A palindromic number reads the same forward and backward. Among the given options, only 12321 is palindromic.

What is the smallest 4-digit number that, when reversed, gives a smaller number?
  • a)
    1000
  • b)
    1001
  • c)
    1100
  • d)
    1010
Correct answer is option 'B'. Can you explain this answer?

Nilotpal Nambiar answered
Explanation:

Given:
The number is a 4-digit number.
When reversed, it gives a smaller number.

Analysis:
To find the smallest 4-digit number that, when reversed, gives a smaller number, we need to consider the position of digits in a 4-digit number.

Steps to Find the Smallest Number:
- Start with the smallest 4-digit number, which is 1000.
- Reversing 1000 gives 0001, which is not a valid 4-digit number.
- Move to the next number, which is 1001.
- Reversing 1001 gives 1001, which is equal to the original number.
- The next number is 1100.
- Reversing 1100 gives 0011, which is a smaller number.
- Hence, the smallest 4-digit number that, when reversed, gives a smaller number is 1100.
Therefore, the correct answer is option B (1100).

In the number sequence for Collatz Conjecture starting with 12, what is the next number after 6?
  • a)
    3
  • b)
    10
  • c)
    7
  • d)
    5
Correct answer is option 'A'. Can you explain this answer?

Nilanjan Unni answered
Understanding the Collatz Conjecture
The Collatz Conjecture is a sequence defined as follows:
- Start with any positive integer.
- If the number is even, divide it by 2.
- If the number is odd, multiply it by 3 and add 1.
- Repeat the process for the resulting number.
Starting with 12
Let's see how the sequence progresses starting with 12:
- 12 (even) → 12 / 2 = 6
- 6 (even) → 6 / 2 = 3
Next Number After 6
Now, we need to find the next number after 6:
- 6 is even, so we divide it by 2:
- 6 / 2 = 3
Thus, after 6, the next number in the sequence is 3.
Options Analysis
Let's review the given options:
- a) 3 (correct answer)
- b) 10 (incorrect)
- c) 7 (incorrect)
- d) 5 (incorrect)
Conclusion
The next number after 6 in the Collatz sequence starting from 12 is indeed 3, making option 'A' the correct choice. This process illustrates how the Collatz Conjecture works, demonstrating the sequence's fascinating and simple rule-based nature.

If a is a whole number such that a + a = a, then a is equal to
  • a)
    0
  • b)
    1
  • c)
    2
  • d)
    none of these
Correct answer is option 'A'. Can you explain this answer?

Akshita Sarkar answered
Understanding the Equation
To solve the equation a + a = a, we need to simplify it.
- The left side, a + a, can be rewritten as 2a.
- Thus, our equation becomes 2a = a.
Rearranging the Equation
Now, let’s rearrange the equation to isolate a:
- Subtract a from both sides:
- 2a - a = 0
- This simplifies to a = 0.
Analyzing the Result
Now, let’s verify if a = 0 satisfies the original equation:
- Substitute a with 0 in the original equation:
- 0 + 0 = 0.
- This is a true statement.
Examining Other Options
Let’s consider the other options briefly to confirm that they do not satisfy the equation:
- If a = 1:
- 1 + 1 = 1
- This simplifies to 2 = 1, which is false.
- If a = 2:
- 2 + 2 = 2
- This simplifies to 4 = 2, which is also false.
- If a = any other whole number:
- The pattern continues, as any whole number n will lead to n + n = n simplifying to 2n = n, resulting in n = 0.
Conclusion
Thus, the only whole number that satisfies the equation a + a = a is:
- Option A: 0.
This confirms that the correct answer is indeed option 'A'.

In the Collatz sequence starting from 21, what is the fourth number?
  • a)
    16
  • b)
    32
  • c)
    64
  • d)
    42
Correct answer is option 'A'. Can you explain this answer?

Gunjan Lakhani answered
The sequence starting from 21 follows 21 → 64 → 32 → 16. The fourth number in the sequence is 16.

Which of the following numbers is a supercell in the grid [45, 78, 92, 31, 20]?
  • a)
    45
  • b)
    31
  • c)
    92
  • d)
    20
Correct answer is option 'C'. Can you explain this answer?

EduRev Class 6 answered
Solution:
A supercell is a number greater than all its neighbouring cells. In the grid [45, 78, 92, 31, 60], we identify the supercell as follows:
  • For 45: Neighbour is 78 (right). Not a supercell.
  • For 78: Neighbours are 45 (left) and 92 (right). Not a supercell.
  • For 92: Neighbours are 78 (left) and 31 (right). This is a supercell.
  • For 31: Neighbours are 92 (left) and 60 (right). Not a supercell.
  • For 20: Neighbour is 31 (left). Not a supercell.
Therefore, the only supercell in the grid is 92.

Which of the following represents a palindromic date?
  • a)
    02/03/2022
  • b)
    10/12/2020
  • c)
    12/02/2021
  • d)
    none of the above 
Correct answer is option 'C'. Can you explain this answer?

Praveen Kumar answered
 palindrome date is 12/02/2021.
When written in the format DD/MM/YYYY, it reads the same forwards and backwards:
12/02/2021 → 12022021 (which is the same forwards and backwards).

Chapter doubts & questions for Number Play - Mathematics for Class 6 2025 is part of Class 6 exam preparation. The chapters have been prepared according to the Class 6 exam syllabus. The Chapter doubts & questions, notes, tests & MCQs are made for Class 6 2025 Exam. Find important definitions, questions, notes, meanings, examples, exercises, MCQs and online tests here.

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