They don't have to, however it's customary for heads of state to meet, especially if they are politically or economically close. As The Queen is the Head of State of 16 countries including the UK & Canada it makes perfect sense to meet at least once during a presidents term.
No. Presidents can be single.
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If the President dies in office, resigns his post, or is impeached and removed, the Vice President steps up to become President and complete the term.
Of the eight U.S. Vice Presidents who advanced to the Presidency due to the death of the sitting President, the first was John Tyler, 31 days after William Henry Harrison's inauguration in 1841.
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the reason why is because when the president dies, becomes ill, or is impeached the vice president takes over.
In order to become president, you have to be at least 35 years old.
8
Via election. He ran and people voted for "him".
Both were vice-presidents who became president when the elected president died in office.
Yes, the president can sign a bill that become a law.