How do you find the least common multiple of 10, 2, and 15?
Observe that 10 is less than 15 so the multiple has to be bigger than 10. Any whole number multiple of 10 will have 0 as its last digit.
2 will be a factor of the LCM so it can not be an odd number.
The multiple of 15 can only have 5 or 0 as its last digit.
So in keeping with the above comments we pick the first multiple of 15 that has a 0 as its last digit (which as it happens, is an even number)
So the LCM is 30