Class 6 Mathematics Notes , Exercise 1.1, Unit-1, Factors and Multiples (New National Book Foundation 2022 and onwards as Federal Text Board Islamabad)

Unit-1: Factors and Multiples

EXERCISE 1.1 

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1. Identify the numbers that have 18 as a factor:

54, 126, 198, 240, 320


Hint: Factor of a number are the numbers that it can be divided exactly by: 

Hint: Check for all the above numbers if divisible by 18 will be the number having 18 as a factor of :


Solution

Checking one by one that the number are completely divisible by 18 or not.

54 ÷ 18 = 3 and remainder 0 (ie. Completely divisible), so 18 is a factor of 54

126 ÷ 18 = 7 and remainder 0 (ie. Completely divisible), so 18 is a factor of 126

198 ÷ 18 = 11 and remainder 0 (ie. Completely divisible), so 18 is a factor of 198

240 ÷ 18 = 13 and remainder 6 (ie. Not Completely divisible), so 18 is not a factor of 54

Among the given numbers, 54, 126, 198 are divisible exactly by 18, s18 is Nota factor of 54

54, 126, 198 -------------Ans.


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2. Identify the numbers below which are factors of 144.

1, 2, 3, 4, 8, 9, 12, 14, 16, 32, 48, 144 

Hint: Factor of a number are the numbers that it can be divided exactly by: 

Hint: Check for all the above numbers that divide 144 exactly will be the answers as a factor of 144:


Solution: 


Factors of 144 are:

144 = 1 x 144
144 = 2 x 72 
144 = 3 x 48
144 = 4 x 36
144 = 6 x 24
144 = 8 x 18
144 = 9 x 16
144 = 12 x 12

All factors of 144 are = 1, 2, 3, 4, 6, 8, 9, 12, 16, 18, 24, 36, 48, 72, 144 

Thus

Answer: 1, 2, 3, 4, 8, 9, 12, 16, 32, 48, 144


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3. Find all factors of:

(i)      15                (ii)    21                (iii)    32
(iv)    29                (v)    40                


Solutions: 


(i)    15   

15 = 1 x 15
15 = 3 ï½˜ 5
15 = 5 ï½˜ 3 (repeating)

All factors of 15 are = 1, 3, 5, 15 --------Ans.(i)



(ii)    21

21 = 1 x 21
21 = 3 ï½˜ 7
21 = 7 ï½˜ 2 (repeating)

All factors of 21 are = 1, 3, 7, 21 --------Ans.(ii)



(iii)    32

32 = 1 x 32
32 = 2 x 16
32 = 4 x 8
32 = 8 ï½˜ 4 (repeating)

All factors of 32 are = 1, 2, 4, 8, 16, 32 --------Ans.(iii)




(iv)    29

29 = 1 x 29
20 = 29 ï½˜ 1 (repeating)

All factors of 29 are = 1, 29 --------Ans.(iv)


(v)    40    

40 = 1 x 40
40 = 2 x 20
40 = 4 x 10
40 = 5 x 8
40 = 8 ï½˜ 5 (repeating)

All factors of 40 are = 1, 2, 4, 5, 8, 10, 20, 40 --------Ans.(v)
   


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4. Write down the first 4 multiples of:

(i)      5                (ii)    6               (iii)    7
(iv)    9                (v)    11              (vi)    14                


Solution: 


(i)       The first 4 multiples of 5 are: 5, 10, 15, 20

(ii)      The first 4 multiples of 6 are: 6, 12, 18, 24

(iii)      The first 4 multiples of 7 are: 7, 14, 21, 28

(iv)      The first 4 multiples of 9 are: 9, 18, 27, 36

(v)      The first 4 multiples of 11 are: 11, 22, 33, 44

(vi)      The first 4 multiples of 14 are: 14, 28, 42, 64


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5. Write down the multiples of 5 between 4 and 31


Solution: 


Multiples of 5 : 5, 10, 15, 20, 25, 30, 35, 40, 45, 50 ...............

Thus multiples of 5 between 4 an31 are: 5, 10, 15, 20, 25,30 ----------Ans.


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6. Identify the multiples of 8 from the following.

14, 24, 32, 54, 56, 72, 30, 64, 18, 40, 78, 96, 106, 120 

Hint: Check for all the above numbers if divisible by 8 completely will be the numbers of multiples of 8:

Solution: 

The highest number is 120. Therefore,

Multiples of 8 up to 120 are : 8, 16, 24, 32, 40, 48, 56, 64, 72, 80, 88, 96, 104, 112, 120.

Now comparing multiples of 8 with question numbers: 24, 32, 56, 72, 64, 40, 96, 120  ----------Ans.



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