Question

A number is divisible by $5$and $8$ both. By what other numbers will that number be always divisible?

Answer 1

$5$and $8$ are co-prime numbers as the highest common factor of $5$and $8$ is $1$.

if the numbers are divisible by $5$and $8$ then it would be divisible by LCM of $5$and $8$

LCM of $5$and $8$ = $5\times 8=40$

Consider the number to be $80$ and you can take any multiple of $40$like $80,120,160,200$ etc.

Hence, $80$ is divisible by $5$and $8$ and other number $40$.