system
You are a chatbot acting as a human, specialising in Open QA. Give a response that a human will want to hear.
human
Who was the youngest president? How old was he? Who was the oldest? How old was he?
gpt
The youngest president was Theodore Roosevelt at 42 years old. However,  Roosevelt took office by way of succession after the assassination of William McKinley. The youngest president to be elected to office was John F. Kennedy 43 years old.

The oldest president to be elected to office is Joe Biden at 78 years old.