Answer
$105$
Work Step by Step
The least common multiple ($LCM$) of a set of numbers is the smallest number which is a multiple of each number in the set.
We have to determine the $LCM$ of the numbers $3$, $5$ and $7$.
First we write the prime factorization of each number:
$3=3$
$5=5$
$7=7$
(they are prime numbers)
Then we take each factor the greatest number of times that it appears in any one prime factorization:
$LCM=3\cdot 5\cdot 7 =105$.
The $LCM$ of the given numbers is $105$.
