Find the least number which when divided by $16, 18, 20$ and $25$ leaves $4$ as a remainder in each case,but when divided by $7$ leaves no remainder.

What is the least number of cut pieces of equal length that can be cut out of two lengths $10\, m\, 857\, mm$ and $15\, m\, 87\, mm$?

Two numbers,both greater than $29$,have $HCF$ $29$ and $LCM$ $4147$. The sum of the numbers is

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?

$A$ heap of stones can be made up into groups of $21$. When made up into groups of $16, 20, 25$ and $45$,there are $3$ stones left in each case. How many stones at least can there be in the heap?

Amit,Sucheta,and Neeti start running around a circular track and complete one round in $18 \text{ seconds}$,$24 \text{ seconds}$,and $32 \text{ seconds}$,respectively. In how many seconds will the three meet again at the starting point if they all started running at the same time?