LCM by Prime Factorization

Q.

Find the LCM of $24,36$and$40$.

Q.

What is the LCM of the numbers 12, 16, 18, 21 and 28?

1. 1008

2. 1012

3. 1022

4. 1010

Q.

Find the LCM of 20, 25, 35, and 40.

1. 7000

2. 1400

3. 700

4. 14000

Q.

Using prime factorisation, find the HCF and LCM of$23,31$. Verify that $HCF\times LCM=productofgivennumbers$

Q. The LCM and HCF of 45, 75 and 30 will be _ and _ respectively.​

1. 450, 30
2. 1, 15
3. 75, 30
4. 450, 15

Q.

Find LCM of the $5,10,15,20$

Q. Three bells toll together at intervals of 9, 12 and 15 minutes. If they start tolling together now, after how much time will they toll together next?

1. 1 hour
2. 2 hours
3. 4 hours
4. 3 hours

Q.

Find the smallest number which is completely divisible by 28 and 42.

1. 48

2. 84

3. 14

4. 28

Q.

Find the least number which when divided by 32, 64 & 128 leaves the remainder of 8.

1. 1024

2. 1034

3. 136

4. 128

Q.

A farmer has 3 storage units for rice. Each storage unit has the same capacity. Rice is available to the farmer in bags of 80 kg, 85 kg and 90 kg. Find the minimum storage capacity of each of the storage unit considering that he has to take rice in bags of 80 kg, 85 kg and 90 kg only.

1. 14220 kg

2. 12240 kg

3. 14422 kg

4. 12440 kg

Q.

Question 10 (b)

Find the LCM of the following numbers:
12 and 5
Observe a common property in the obtained LCMs. Is LCM the product of two numbers in each case?

Q. Match the following.

1. 8
2. 1331
3. 4
4. 24

Q.

There are 3 taps. Water starts to drip from the three taps. A drop of water comes out of first, second and third tap every 2 seconds, 4 seconds and 7 seconds respectively. After how many seconds will the drops of water from all the three taps fall together?

1. 14 seconds

2. 28 seconds

3. 42 seconds

4. 56 seconds

Q. Which of the following is a common multiple of 5, 6 and 7?

1. 230
2. 210
3. 140
4. 310

Q. What is the smallest number which when divided by 20, 25, 35, 40 leaves a remainder of 14, 19, 29 and 34 respectively?

1. 1404
2. 1394
3. 1606
4. 1406

Q. What is the smallest number which when decreased by 7 is exactly divisible by 12, 16, 18, 21 and 28?

1. 1022
2. 1008
3. 1015
4. 1012

Q.

What is the LCM of the numbers 12, 16, 18, 21 and 28?

1. 1008

2. 1012

3. 1022

4. 1010

Q. Four bells commence tolling together and then toll at intervals of 6, 7, 8 and 9 seconds respectively. After how many seconds do all the bells ring together?

1. 504
2. 512
3. 516
4. 508

Q.

Samaira heard 3 bells toll together at 10:00 AM. The first bell tolls after every 5 second, the second tolls after every 9 seconds and the third tolls after every 10 seconds. When will they toll together again?

1. After 2 minutes and 30 seconds
2. After 45 seconds
3. After 3 minutes
4. After 90 seconds