Arihant Expert Team (AET) Solutions for Exercise 1: CHAPTER EXERCISE

(Smallest common multiple of $36, 60$ and $72$) $÷$ (Biggest common factor of $18, 45$ and $36$) is equal to:

The HCF and LCM of two numbers are $13$ and $1989$, respectively. If one of the numbers is $117$, then determine the other.

The HCF of two numbers is $15$ and their LCM is $225$. If one of the numbers is $75$, then find the another number.

If the HCF of the two numbers are $3$, then which of the following can never be their LCM?

There are three street lights which get on for one second after $30 s, 40 s$ and $50 s$ espectively. If last time they were on simultaneously at $4 : 00$ pm, at what time after $4 : 00$ pm all of them get on again simultaneously?

Find the least number which, when divided by $12, 16, 24$ and $36$, leaves a remainder $7$ in each case.

A gardener wants to plant trees in a garden. If the number of trees in each row is the same and there are $20$ or $40$ or $60$ row, then no tree is left. Find the least number of trees the gardener has:

There are three bells which ring after $30 \min$, $80 \min$ and $90 \min$, respectively. If last time they rang simultaneously at $8 : 30$ am. At what time they will again ringing simultaneously ?