Conversation so far:
who was the highest paid president of the united states
Since 2001, the United States President's salary has been $400,000
which president of the united states had the highest networth
The richest president in history is Donald Trump, who is the first billionaire president. His net worth, however, is not known precisely because the Trump Organization is privately held.
what is president donald trump's estimate networth
By estimate, Trump is wealthier than all former presidents combined.
what is president donald trump's estimate networth in us dollars
In its 2018 billionaires ranking, Forbes estimated Trump's net worth at $3.1 billion.

Question: what about obama
Self-contained rewrite: what is president obama's networth in us dollars