What is the smallest number of marbles that could be divided up either into bags of $18$ marbles or into bags of $42$ marbles, with no marbles left over in each case?
<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
What is the smallest number of marbles that could be divided up either into bags of $18$ marbles or into bags of $42$ marbles, with no marbles left over in each case?
Please reason step by step, and put your final answer within \boxed{{}}.<|im_end|>
<|im_start|>assistant

user
126
What is the smallest number of marbles that could be divided up either into bags of $18$ marbles or into bags of $42$ marbles, with no marbles left over in each case?
train