<Tr> <Td> 1 / 10 </Td> <Td> 7 </Td> <Td> 7 + 0.7 + 0.07 + 0.007 + 0.0007 + </Td> </Tr> <Tr> <Td> </Td> <Td> </Td> <Td> 3 + 3 + 3 + 3 + 3 + </Td> </Tr> <Tr> <Td> − 1 / 2 </Td> <Td> </Td> <Td> 1 − 1 / 2 + 1 / 4 − 1 / 8 + 1 / 16 − 1 / 32 + </Td> </Tr> <Tr> <Td>--1 </Td> <Td> </Td> <Td> 3 − 3 + 3 − 3 + 3 − </Td> </Tr>

Formula for the sum of a geometric series