<Table> <Tr> <Th_colspan="2"> Vice President of the United States of America </Th> </Tr> <Tr> <Td_colspan="2"> Vice Presidential seal </Td> </Tr> <Tr> <Td_colspan="2"> Vice Presidential standard </Td> </Tr> <Tr> <Td_colspan="2"> Incumbent Mike Pence since January 20, 2017 </Td> </Tr> <Tr> <Td_colspan="2"> Executive branch of the U.S. government Office of the Vice President </Td> </Tr> <Tr> <Th> Style </Th> <Td> Mr. Vice President (Informal) The Honorable (Formal) Mr. President (When presiding over Senate) His Excellency (In international correspondence) </Td> </Tr> <Tr> <Th> Member of </Th> <Td> Cabinet National Security Council President of the U.S. Senate </Td> </Tr> <Tr> <Th> Residence </Th> <Td> Number One Observatory Circle </Td> </Tr> <Tr> <Th> Seat </Th> <Td> Washington, D.C. </Td> </Tr> <Tr> <Th> Appointer </Th> <Td> Electoral College </Td> </Tr> <Tr> <Th> Term length </Th> <Td> 4 years </Td> </Tr> <Tr> <Th> Constituting instrument </Th> <Td> U.S. Constitution </Td> </Tr> <Tr> <Th> Inaugural holder </Th> <Td> John Adams (April 21, 1789) </Td> </Tr> <Tr> <Th> Formation </Th> <Td> March 4, 1789 (229 years ago) (1789 - 03 - 04) </Td> </Tr> <Tr> <Th> Succession </Th> <Td> First </Td> </Tr> <Tr> <Th> Salary </Th> <Td> $230,700 </Td> </Tr> <Tr> <Th> Website </Th> <Td> WhiteHouse.gov </Td> </Tr> </Table> <Tr> <Th_colspan="2"> Vice President of the United States of America </Th> </Tr>

What role does the vice president serve in the senate when is the only time he can vote