### Discussion :: Series Completion - Section 1 (Q.No.4)

Choose the correct alternative that will continue the same pattern and replace the question mark in the given series.

Prem said: (Jul 18, 2011) | |

We have to go with formula only ? |

Aman said: (Jul 24, 2011) | |

Not understandable. |

Kanna said: (Aug 16, 2011) | |

If we don't know formula we can go in simple logic 2,6,18,54,5th term,6th term,7th term,8th term(here we should get answeer) So 2 x 3 = 6, 6 x 3 = 18, 18 x 3 = 54, 54 x 3=162(5th term), 162 x 3=486(6th term), 486 x 3=1458(7th term), 1458 x 3=4374(8th term and our answer) |

Appy said: (Aug 19, 2012) | |

How do we find 3^7 without using " calculator and multiplying 3 seven times " ? please tell me the easy method to find out a number raised to a large power. |

Bhumika said: (Sep 9, 2012) | |

I dont understand the answer.2,6,18,54,5th term,6th term,7th term,8th term(here we should get answeer) .how it comes 4374 |

Aswini said: (Oct 14, 2012) | |

What does GP mean?can anyone explain me please. |

Avinash Wadhe said: (Nov 22, 2012) | |

GP means Geometric Progression formula. |

Sahiba said: (May 23, 2013) | |

Geometric progression is one where a set of numbers vary with one number which is multiplied to each one to get the next term. Ex:2(2*3) = 6(6*3) = 18.... So now 2 6 18... are in gp differing by 3 each. |

Arif said: (Jun 28, 2013) | |

There should be some easy method to solve this, Can any one have? |

Biji said: (Aug 1, 2013) | |

A = 2. R = 3. N = 8 th term. = 2*3^(8-1). = 2*3^7. = 2(3^7) = 2(3^2 * 3^2 * 3^2 * 3). = 2(9*9*9*3) = 2(81*27). = 2(2187) = 4374. 3^7 = 3 square * 3 Square * 3 Square * 3. |

Sameer said: (Nov 7, 2013) | |

@Kanna. Why we need to multiply with 3 With Given Numbers? |

Manjot Singh said: (Mar 1, 2014) | |

2*3 = 6. 6*3 = 18. 18*3 = 54. 54*3 = 162. 162*3 = 486. 486*3 = 1458. 1458*3 = 4374. |

Sangeeta said: (Nov 26, 2014) | |

This series is in geometric progression: So 8th term is = 2*3^(8-1). = 2*3^(7). = 2*3^(4+3). = 2*[3^4*3^3]. = 2*[81*27]. = 2*2187. = 4374. |

Chiran said: (Feb 8, 2015) | |

What is the meaning of a and r please explain me? |

Kanhay said: (Feb 8, 2015) | |

A means first term and are means common ratio. |

Upender Singh Rajput said: (Jul 19, 2015) | |

Solving with GP. (Geometrical Progression) find 8th term. Now Series is 2 6 18 54.....8th term. So a =2, r=6\2=3, T8=2(3)7, T8 = 4374. |

Nrusingha Acharya said: (Jan 21, 2016) | |

An other method: 2. 6*3^0. 6*3^1. 6*3^2. 6*3^3. 6*3^4. 6*3^5. 6*3^6, Only calculate the 8th one not all and get the result. |

Sameer said: (Jan 26, 2016) | |

Why ^7 instead ^8 because there find out 8th place? |

Nigerian Boy said: (Feb 22, 2016) | |

@Sameer. From the formula T8 = ar (power N-1). N stands for Number of terms you are looking for so all you need do is know that you have to subtract 1 from the number of terms. Eg. 1. When the number of terms in question is 9 then the formula becomes T9 = ar9-1. 2. When it is 5 the formula becomes T5 = ar5-1. |

Vaishnavi said: (May 21, 2016) | |

Yes, using formula is also the correct method. |

Amrit Hayer said: (Aug 11, 2016) | |

The sum of first 3 terms of G.P is 16 and the sum of next 3 terms is 128. Find 1st term, common ratio and sum 20 terms? please solve this. |

Madalin said: (Jul 13, 2021) | |

2 + 2 = 4 + 2 = 6, 6 + 6 = 12 + 6 = 18, 18 + 18 = 36 + 18 = 54, 54 + 54 = 108 + 54 = 162, 162 + 162 = 324 + 162 = 486, 486 + 486 = 972 + 486 = 1458, 1458 + 1458 = 2916 + 1458 = 4374. 2, 6, 18, 54, 162, 486, 1458, 4374. 8th term is 4374. |

Papai said: (Aug 9, 2021) | |

ar^n-1 where n=no of term, a=first elementary. So, 2*3^7=4374. |

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