Multiples


 
 
Concept Explanation
 

Multiples

Multiples:

When we write a number 20 as 20=4times 5,  we say 4 and 5 are factors of 20. We also say that 20 is a multiple of 4 and 5.

         The representation 24=2times 12, shows that 2 and 12 are factors of 24, whereas 24 is a multiple of 2 and 12.

We say that the numbers 3, 6, 9, 12, 15 are multiples of 3.

The list of multiples of 3 can be continued as 18, 21, 24,...

Each of these multiples is greater than or equal to 3.

The multiple of the number 4 are 4, 8, 12, 16, 20, 24,...

The list is endless. Each of these numbers is greater than or equal to 4.

1. What are the multiples of 7? Obviously, 7, 14, 21, 28,... You will find that each of these multiples is greater than or equal to 7. Will it happen with each number? Check this for the multiples of 6, 9 and 10.

    We find that every multiple of a number is greater than or equal to that number.

2. Write the multiples of 5. They are 5, 10, 15, 20,... Do you think this list will end anywhere? No! The list is endless. Try it with multiples of 6, 7 etc.

   We find that the number of multiples of a given number is infinite.

3. Can 7 be a multiple of itself? Yes, becuase 7=7times 1, Will it be true for other numbers also? Try it iwth 3, 12 and 16.

    You will find that every number is a multiple of itself.

    The factor f 6 are 1, 2, 3 and 6 . Also, 1+2+3+6 = 12 = 2 times 6. We find that the sum of the factor of 6 is twice the number 6. All the factors of 28 are 1,2,4,7,14, and 28. Adding these we have, 1+2+4+7+14+28 = 56 = 2 times 28.

   The sum of the factors of 28 is equal to twice the number 28.

4. A number for which sum of all its factors is equal to twice the number is called a perfect number. The numbers 6 and 28 are perfect numbers.

Sample Questions
(More Questions for each concept available in Login)
Question : 1

How many odd numbers are there between 20 and 50 ?

Right Option : B
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Explanation
Question : 2

Find the two consecutive odd numbers whose sum is 84.

Right Option : C
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Explanation
Question : 3

Find the multiple of 5 which lies in between 17 and 23.

Right Option : B
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Explanation
 
 
 


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