Three bells ring together and they will ring at intervals of $6$ seconds,$7$ seconds and $8$ seconds respectively. After what interval will they again ring together? (in seconds)

Find the greatest number of five digits which when divided by $12, 15, 21, 25$ and $28$ leaves $5, 8, 14, 18$ and $21$ as remainders, respectively.

In a school,$391$ boys and $323$ girls have been divided into the largest possible equal classes,so that each class of boys numbers the same as each class of girls. What is the number of classes?

The traffic lights at three different road crossings change after $24$ seconds,$36$ seconds,and $54$ seconds,respectively. If they all change simultaneously at $10:15:00$ am,then at what time will they again change simultaneously?

Three numbers are in the ratio $1: 2: 3$ and their $HCF$ is $12$. The numbers are:

The largest natural number which exactly divides the product of any four consecutive natural numbers is