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View Full Version : What is the formula of the series 8,11,14,17,20


Rollyn
Feb 6, 2013, 08:13 PM
What is the rule for generating this sequence 8, 11,14,17,20

MikeBear
Feb 7, 2013, 10:08 AM
What does all these numbers have in common? I saw a relationship the first time I saw them. Look more closely, and I think you can figure it out.

dontknownuthin
Feb 7, 2013, 11:17 AM
We can't do your homework for you but we can help you learn to do it yourself. I will give you two other examples to explain how to do this.

There are two parts to figure out this question:

FIRST, FIND THE PATTERN:

For example, if your number series were 2, 4, 6, 8, 10, you would recognize that this is the series of even numbers. But you have to express that in a formula, so you have to figure out, "what do I do to each number in the series to get to the next number in the series?" You add 2 to each number to get to the next one.

SECOND, EXPRESS THE PATTERN BY STATING THE RULE:

+2

To test your rule, try it all the way through:

2 + 2 = 4
4 + 2 = 6
6 + 2 = 8
8 + 2 = 10

We got the right sequence of numbers in the right order, so the rule works.

Here's another one:

1, 3, 9, 27, 81

This looks pretty random until you start playing around with it. Try what to add, multiply, divide, subtract until you find something that works all the way through. In this case, I figured out that the rule is: x 3

To test my rule I multiply each number in my series by three and see if I get the correct next number:

1 x 3 = 3
3 x 3 = 9
9 x 3 = 27
27 x 3 = 81

1,3,9,27, 81... yep, it worked.

Now try it with your series and please post your answer...

You will probably be asked to figure out the next number in the series. Just apply the rule to the last number, and you'll get the next number.