Compute: $\sqrt{15 \cdot 35 \cdot 21}$.
<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
Compute: $\sqrt{15 \cdot 35 \cdot 21}$.
Please reason step by step, and put your final answer within \boxed{{}}.<|im_end|>
<|im_start|>assistant

user
105
Compute: $\sqrt{15 \cdot 35 \cdot 21}$.
train