Question

Which rule best describes the pattern?

3, 9, 27, 81, ___, ____, ___
A. Add by 6
B. Add by 6, add by 18
C. Divide by 3
D. Multiply by 3

Answer 1

D. Multiply by 3

Explanation:

Given:

• A sequence 3,9,27,81,__,__,__

To find:

• Pattern

Notice that if you keep multiplying by 3:

• 3*3 = 9
• 9*3 = 27
• 27*3 = 81

Then you will get exact sequence as given, so next 3 missing terms have to be:

• 81*3 = 243
• 243*3 = 729
• 729*3 = 2187

Hence, the pattern for this sequence is to multiply by 3.

Note

• This given sequence is called Geometric Sequence, a sequence with common ratio.
• Common Ratio can be found by dividing next term with previous term. (I.e. 9/3 = 3 so a common ratio for this sequence is 3)
• By multiplying previous term with a common ratio, you get the next term.