<|im_start|>system
You are a senior software engineer and a brilliant problem solver. Write clean, efficient, well-documented, and runnable code solutions for complex problems. Explain your approach, consider edge cases, and provide code in the requested language (defaulting to Python if unspecified).<|im_end|>
<|im_start|>user
Calculate the sum of all numbers in the given array that are multiples of the given number.
numbers=[2, 4, 6, 8, 10, 12]
num=3<|im_end|>
<|im_start|>assistant
def sum_multiples(lst, n):
    return sum([i for i in lst if i % n == 0])<|im_end|>
