Math CentralQuandaries & Queries


Question from Grace, a parent:

What number best completes the series?

2 3 7 13 27 ____


We have two responses for you

Hi Grace.

Here's a hint. A Fibonacci sequence takes the last value and adds the value previous to it to form the next value:
..., 5, 8, 13, 21, 34, ....
8 + 5 = 13
13 + 8 = 21

Your sequence is very similar to this, but there is a factor of 2 involved as well.

Stephen La Rocque.


Try doubling the previous number - does that give you a clue?


Grace wrote back

Is the answer 54?


How did you arrive at 54? With these "next term in the sequence" problems there are many possible answers. What is important is how you arrived at your answer.


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