Question

What is the lcm of 3,9, and 15?

Answer 1

The LCM of any set of numbers that has a prime or a number of primes in common.  The way to find it is to factor the given number down to it's primes.

3: 3

9: 3 * 3

15: 3 * 5

The number which has been bolded is the LCM in this case 3 <<<< Answer

This is not a particularly good question to learn what it might be Try these 3 numbers.

42: 2*3 * 7

84: 2 * 2 * 3 * 7

210: 2*5 * 3 * 7

The LCM for this bunch is 2 * 3 * 7 = 42

Answer 2

The least common multiple that is common in all numbers but is the lowest is 3 and it's the only number that all numbers listed can be divided easily by.

Hope this helps!