<Table> <Tr> <Td> </Td> <Td> This section may stray from the topic of the article into the topic of another article, Geometric series . Please help improve this section or discuss this issue on the talk page . (February 2014) </Td> </Tr> </Table> <Tr> <Td> </Td> <Td> This section may stray from the topic of the article into the topic of another article, Geometric series . Please help improve this section or discuss this issue on the talk page . (February 2014) </Td> </Tr> <Table> <Tr> <Td> </Td> <Td> </Td> <Td> + </Td> <Td> 10 </Td> <Td> + </Td> <Td> 50 </Td> <Td> + </Td> <Td> 250 </Td> <Td> </Td> <Td> </Td> <Td> = </Td> <Td> 312 </Td> </Tr> <Tr> <Td> − (</Td> <Td> </Td> <Td> </Td> <Td> 10 </Td> <Td> + </Td> <Td> 50 </Td> <Td> + </Td> <Td> 250 </Td> <Td> + </Td> <Td> 1250 </Td> <Td> = </Td> <Td> 5 × 312) </Td> </Tr> <Tr> <Td_colspan="12"> </Td> </Tr> <Tr> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> − </Td> <Td> 1250 </Td> <Td> = </Td> <Td> (1 − 5) × 312 </Td> </Tr> </Table> <Tr> <Td> </Td> <Td> </Td> <Td> + </Td> <Td> 10 </Td> <Td> + </Td> <Td> 50 </Td> <Td> + </Td> <Td> 250 </Td> <Td> </Td> <Td> </Td> <Td> = </Td> <Td> 312 </Td> </Tr>

Sum of geometric progression when r is less than 1