Applications of LCM

Q.

How to convert $128$ in binary ?

Q.

The LCM of two numbers is $25$ times their HCF. the product of the two numbers is $2025$. Find the HCF.

1. $81$

2. $45$

3. $9$

4. $18$

Q.

If the LCM of two numbers $21$ and $30$ is $210$, what is their HCF?

Q.

HCF and LCM of two numbers $a$ and $b$ obeys the rule HCF$\times$LCM = ___________

Q. Mini is standing in front of three lights which are turning on and off. She observes the lights lit up after every 10, 12 and 15 minutes respectively. If all the lights lit up together for the last time at 1 P. M. At what time will they lit up together again?

1. 1:45 PM
2. 2 PM
3. 3 PM
4. 5 PM

Q. I have 20 oranges. What is the least number of oranges I need to take such that I can divide the oranges into groups of 6 or groups of 9 without leftovers?

1. 15
2. 18
3. 9
4. 12

Q.

Manu goes to dance class once in every 6 days, to karate class once in every 12 days and to art classes once in every 18 days. He attends all the three classes on 1st of April. On which day, will he attend all the 3 classes again?

1. 8th May

2. 7th May

3. 1st May

4. 21st April

Q. Four bells commence tolling together at 1: 00 pm and toll at intervals of 2, 4, 6 and 8 minutes respectively. At what time will the bells toll together again?

1. 1 : 28 pm
2. 1 : 20 pm
3. 1 : 16 pm
4. 1 : 24 pm