What is the units digit when $7^{53}$ is multiplied out?
<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
What is the units digit when $7^{53}$ is multiplied out?
Please reason step by step, and put your final answer within \boxed{{}}.<|im_end|>
<|im_start|>assistant

user
7
What is the units digit when $7^{53}$ is multiplied out?
train