How many terms of the sequence $\sqrt{1},\sqrt{2},\sqrt{3},\sqrt{4},\ldots$ are less than or equal to $20$?
<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
How many terms of the sequence $\sqrt{1},\sqrt{2},\sqrt{3},\sqrt{4},\ldots$ are less than or equal to $20$?
Please reason step by step, and put your final answer within \boxed{{}}.<|im_end|>
<|im_start|>assistant

user
400
How many terms of the sequence $\sqrt{1},\sqrt{2},\sqrt{3},\sqrt{4},\ldots$ are less than or equal to $20$?
train