HCF and LCM

 Find the $\mathrm{H}.\mathrm{C}.\mathrm{F}.$ of$\frac{2}{3} ,\frac{4}{5}$  and $\frac{6}{7}$ 

Two numbers are in the ratio 4 : 5 and their LCM is 180, then find the smaller number?

The LCM of two numbers is$30$ and their HCF is $5.$ One of the number is $10.$ The other is -

Six bells commence tolling together at intervals of $2,4,6,8,10$and $12 \mathrm{seconds}$ respectively. In $30 \mathrm{minutes}$. How many times do they toll together?

Consider the following pairs:

A. $5 and 105$

B. $15 and 105$

C. $15 and 35$

A, B and C walk $1 km$ in $5$ minutes, $8$ minutes and $10$ minutes respectively. C starts from a point, B starts from the same point after $1$ minute and A starts from the same point $2$ minutes after C. In how much time will A meet B and C?

What is the least possible number which when divided by $10, 12, 15, 18$ it leaves the reminder $6, 8, 11, 14$ respectively?

There are three sets of Biology, chemistry and Math test papers containing $96$, $120$ and $144$ papers respectively have to be stacked in such a way that all the test papers are stored subject wise and height of each stack is same. Total number of stack will be _____.

A certain type of board is sold in length of multiples of $2$ ft. The shortest board sold is $6$ ft and the longest board sold is $24$ ft. A builder needs a large quantity of these types of boards in $5\frac{1}{2}$ft lengths. Find the length to be ordered for which waste is minimum?

The LCM of$\frac{2}{3}, \frac{3}{4}, \frac{4}{5}, \frac{5}{6},\frac{6}{7}$  is -

The HCF and LCM of two positive integers are 35 and 385 respectively. If one of the integers is 77, what is the other integer?

The sum of four consecutive even number is 284. What would be the smallest number?

If the sum of two numbers is $55$ and the h.c.f. and l.c.m. of these numbers are $5$ and $120$ respectively, then the sum of the reciprocals of the numbers is equal to:

The H.C.F. of $\frac{9}{10}, \frac{12}{25},\frac{18}{35}$ and $\frac{21}{40}$ is:

Reduce to  $\frac{128352}{238368}$  its lowest terms.

The LCM of two number is 2079 and then HCF is 27. If one of the number is 18.9, find the other:

A, B and C start at the same time in the same direction to run around a circular stadium. A completes a round in 252 seconds, B in 308 seconds and c in 198 seconds, all starting at the same point. After what time will they again at the starting point ? 

Tanu , Priya and and Sony started to run around a circular stadium and complete a round in 36 seconds ,9 seconds and 45 seconds respectively . In what time will they meet at the strating point?

Three friends A, B and C start running around a circular stadium and complete a single round in 8, 18 and 15 seconds respectively. After how many minutes will they meet again at the starting point for the first time?

Find the lowest common multiple of 24, 36 and 40.