Simplify $(1)(2a)(3a^2)(4a^3)(5a^4)$.
<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
Simplify $(1)(2a)(3a^2)(4a^3)(5a^4)$.
Please reason step by step, and put your final answer within \boxed{{}}.<|im_end|>
<|im_start|>assistant

user
120a^{10}
Simplify $(1)(2a)(3a^2)(4a^3)(5a^4)$.
train