Ageometric sequence is a sequence of numbers where each successive number is determined by multiplying by a constant value, called the common ratio. consider the sequence 2, 6, 18, 54,….

We know that this sequence is a geometric sequence, with a constant ratio. 

6/2=3
18/6=3
54/18=3

As seen, the common ratio is 3 for this sequence. 

54×3=162 
162×3=486 
486×3=1458 

Hope I helped :)