How many terms of the series `1+2+2^2+…..` must be taken to make 511?

How many terms of the series 15+12+9+... must be taken to make 15? Explain the double answer.

How many terms of the series 54 + 51 + 48 + … must be taken to make 513 ? Explain ? Explain the -double anwer.

How many terms of the series 54 + 51 + 48 + … must be taken to make 513 ? Explain ? Explain the -double anwer.

How many terms of the series 2 +6+ 18+ ... must be taken to make the sum equal to 728?

How many terms of the series 54+51+48+45+ ... must be taken to make 513 ? Explain the double answer.

How many terms of the series 2+6+18+ ... Must be taken to make the sum equal to 728 ?