Numbers | Term 2 Chapter 2 | 5th Maths - Exercise 2.2 (Least Common Multiple LCM) | 5th Maths : Term 2 Unit 2 : Numbers
Chapter: 5th Maths : Term 2 Unit 2 : Numbers
Exercise 2.2 (Least Common Multiple LCM)
Exercise 2.2
1. Choose
the best answer:
(i) The number
divisible by 5 with no remainder
a.
14
b.
535
c.
447
d.
316
Answer: b.
535
(ii) Pick the number
which is not a multiple of 6.
a.
18
b.
26
c.
72
d.
36
Answer:
b. 26
(iii) The common
multiple of 4 and 8 among the given number is.
a.
32
b.
84
c.
68
d.
76
Answer:
a. 32
(iv) Factors of 6
a.1,
2, 3
b.
1, 6
c.
1, 2, 3, 6
d.
2, 3
Answer:
c. 1, 2, 3, 6
v) Multiple of 9 is
a.79
b.
87
c.
29
d.
72
Answer:
d. 72
2. Fill
in the blanks:
(i)
Factors of 7 1
, 7
(ii)
The only even prime number is 2
(iii)
L.C.M of 4, 12 12
(iv)
L.C.M of 5, 15 15
(v)
The numbers which divides 35 without reminders are 1, 5, 7
3. Write
down the factors of the given numbers.
(i)
25
(ii)
36
(iii)
14
(iv)
16
(v)
12
i)
The factors of 25 are 1, 5, 25
ii)
The factors of 36 are 1, 2, 3, 4, 6, 9, 12, 18, 36
iii)
The factors of 14 are 1, 2, 7, 14
iv)
The factors of 16 are 1, 2, 4, 8, 16
v)
The factors of 12 are 1, 2, 3, 4, 6, 12
4. Draw a
picture of factor tree.
(i) 18
(ii) 33
(iii) 16
(iv) 50
5. Write
down the first 5 multiples of the given numbers.
(i) 7
i) The first 5 multiples of 7 are
7, 14, 21,
28, 35
(ii) 9
The first 5 multiples of 9 are
9, 18, 27,
36, 45
iii) 16
The first 5 multiples of 16 are
16, 32,
48, 64, 80
(iv) 11
The first 5 multiples of 11 are
11, 22,
33, 44, 55
(v) 21
The first 5 multiples of 21 are
21, 42,
63, 84, 105
6. Find
first three common multiples of the given numbers.
(i) 24, 16
(ii) 12, 9
(iii) 24, 36
i.
Multiples of 24 and 16
Multiples of 24 are 24, 48, 72, 96, 120, 144, 168
Multiples of 16 are 16, 32, 48, 64, 80, 96, 112, 128, 144
The common multiples of 24 and 16 are 48, 96, 144
ii.
Multiples of 12 and 9
Multiples of 12 are 12, 24, 36, 48, 60, 72, 84, 96, 108, 120
Multiples of 9 are 9, 18, 27, 36, 45, 54, 63, 72, 81, 90, 99,
108, 117
The common multiples of 12 and 9 are 36, 72, 108
iii.
Multiples of 24 and 36
Multiples of 24 are 24, 48, 72, 96, 120, 144, 168, 192, 216,
240, 264, 288
Multiples of 36 are 36, 72, 108, 144, 180, 216, 252, 288
The common multiples of 24 and 36 are 144, 288, 432
7. Find
L.C.M of the given numbers.
(i) 12 and 28
(ii) 16 and 24
(iii) 8 and 14
(iv) 30 and 20
i) 12 and
28
Multiples of 12 are 12, 24, 36, 48, 60, 72, 84, 96, 108, 120,
132, 144, 156, 168….
Multiples of 28 are 28, 56, 84, 112, 140,168,196....
Common multiples of 12 and 28 are 84, 168, …
LCM of 12
and 28 is 84
ii) 16
and 24
Multiples of 16 are 16, 32, 48, 64, 80, 96, 112, 128, 144, 160….
Multiples of 24 are 24, 48, 72, 96, 120, 144, ….
Common multiples of 16 and 24 are 48, 96, 144....
LCM of 16 and 24 is 48
iii) 8
and 14
Multiples of 8 are 8, 16, 24, 32, 40, 48, 56, 64, 72, 80,
88, 96, 104, 112, ….
Multiples of 14 are 14, 28, 42, 56, 70, 84, 98, 112, 126, ....
Common multiples of 8 and 14 are 56, 112, ….
LCM of 8
and 14 is 56
iv) 30
and 20
Multiples of 30 are 30, 60, 90, 120, 150, 180, 210, 240, 270,
360....
Multiples of 20 are 20, 40, 60, 80, 100, 120, 140, 160, 180, 200
Common multiples of 30 and 20 are 60, 120, 180
LCM of 30
and 20 is 60
8. Ramya visits the gym
five days once and Kavitha visits the gym six days once. In which day will they
meet each other?
Ramya visits the gym 5 days once Kavitha visits the gym, 6 days
once
We have to find LCM of 5 and 6
LCM of 5, 6
5
= 1×5
6 =
2×3
LCM
of 5, 6 = 2 × 3 × 5 = 30
They
both will meet 30th day.
9. Arun and shahjahan
goes for walking in a circular path of a park in the same direction. Arun takes
6 minutes to complete one round, while shahjahan takes 8 minutes to complete
one round. In how many minutes will they meet each other?
Arun takes 6 minutes to complete one round. Shanjahan minutes to
complete one round.
We have to take LCM of 6,8
6= 2 × 3
8= 2×2×2
LCM of 6 and 8 = 2 × 2 × 2 × 3 = 24
They both will meet at 24th minute.
Answer:
Exercise 2.2
1. i)
b.535 ii) b. 26 iii) a. 32 iv) c. 1,2,3,6 v) d. 72
2. i) 1,7
ii) 2 iii) 12 iv) 15 v) 1,5,7
3. i)
1,5,25 ii) 1,2,3,4,6,9,12,18,36 iii) 1,2,7,14 iv) 1,2,4,8,16 v) 1,2,3,4,6,12
4.
5. i) 7,
14, 21, 28, 35 ii) 9, 18, 27, 36, 45 iii) 16, 32, 48, 64, 80 iv) 11, 22, 33,
44, 55 v) 21, 42, 63, 84, 104
6. i) 48,
96, 144 ii) 108, 216, 324 iii) 864, 1728, 2592
7. i) 84
ii) 48 iii) 56 iv) 60
8. 30th
day
9. 24
minutes
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