Question

Find the indicated term of the given geometric sequence, a1=18, r=2.1, n=12

Answer 1

The general term of a geometric sequence is
  an = a1·r^(n-1)
Fill in the given numbers and do the arithmetic.
  a12 = 18·2.1^(12-1)
  a12 = 63,049.95009759978

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When a number with one decimal place is raised to the 11th power, the result is a number with 11 decimal places. It would seem you are expected to round this to some lesser number of decimal places. The number shown is exact. You can round it according to your needs.