What is the next number in the sequence 25, 27, 30, 15, 5, 7, 10?

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In summary, the conversation discusses a basic math problem about finding the next number in a sequence. The author suggests a solution of +2, +3, divided by 2, divided by 3, +2, +3, divided by 2, and so on. However, the correct answer is -5, which the author finds surprising and questions whether it could be a typo. Another participant in the conversation points out that there is no definitive "right" answer and suggests another possible solution. The conversation concludes with the author realizing the importance of keeping things simple when approaching these types of problems.
  • #1
Drksilver163
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Hi,

so i am working on some basic math problems and i get this problem about finding the next number in the sequence, and this is it:

25, 27, 30, 15, 5, 7, 10 __


I see the simple solution as +2, +3, divided by 2, divided by 3, +2, +3, divided by 2 and so on...

So given my possible solution the answer should be 5, right? Wrong. Apparently the solution is -5. I don't see how this can be, unless I am missing something. Could the answer indeed be 5 and the negative is a typo? Any help would put my mind at ease, thanks.

Marco
 
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  • #2
Welcome to PF!

Hi Marco! Welcome to PF! :smile:
​
Why divison?

Why not stay with addition and subtraction? :wink:
 
  • #3
Drksilver163 said:
Apparently the solution is -5.
Do keep in mind that these kinds questions don't really have a "right" answer. Presumably the author had some rule in mind, but that rule cannot be known from just those 7 points of data. (In fact, it can't be known unless you know every term in the sequence!)

You shouldn't really feel bad that your guess was not what the author had in mind. But you should be able to field another guess now that you know what the next term actually is
 
  • #4
tiny-tim said:
Hi Marco! Welcome to PF! :smile:
​
Why divison?

Why not stay with addition and subtraction? :wink:

I see...for some reason that thought didnt pop into my head cause whenever i look at these sequence problems i tend to over-think. Thanks a lot, this shows me to keep things more simple.

And thanks for the welcome :biggrin:

Hurkyl said:
Do keep in mind that these kinds questions don't really have a "right" answer. Presumably the author had some rule in mind, but that rule cannot be known from just those 7 points of data. (In fact, it can't be known unless you know every term in the sequence!)

You shouldn't really feel bad that your guess was not what the author had in mind. But you should be able to field another guess now that you know what the next term actually is

Thanks for your input as well. Seems to me like both can be a viable solution given the data points.
 
  • #5
yep +2, +3, -15, -10, +2, +3, -15, -10
 

FAQ: What is the next number in the sequence 25, 27, 30, 15, 5, 7, 10?

What is a number sequence problem?

A number sequence problem is a type of mathematical puzzle where a series of numbers is given and the pattern or rule behind the sequence needs to be identified. The goal is to determine the next number in the sequence or to fill in any missing numbers.

How do you solve a number sequence problem?

To solve a number sequence problem, you need to carefully observe the given numbers and look for any patterns or rules. These can be based on arithmetic operations (such as addition, subtraction, multiplication, or division), geometric patterns, or other mathematical concepts. Once you have identified the pattern, you can use it to determine the missing numbers or predict the next number in the sequence.

What strategies can be used to solve number sequence problems?

Some strategies that can be used to solve number sequence problems include looking for common arithmetic operations (such as adding or multiplying by a constant number), identifying geometric patterns (such as doubling or halving), and considering the position of the numbers in the sequence (such as the difference between adjacent numbers). It can also be helpful to try different patterns or rules until one fits all the given numbers.

Are there any tips for solving number sequence problems?

Some tips for solving number sequence problems include starting with simple sequences and gradually moving on to more complex ones, drawing diagrams or visual aids to help identify patterns, and using trial and error to test different patterns. It can also be helpful to break the sequence into smaller parts or subsets and look for patterns within those subsets.

How can number sequence problems be used in real life?

Number sequence problems can be used in real life to help with problem-solving skills, critical thinking, and mathematical reasoning. They are also commonly used in cognitive tests and assessments. In addition, understanding number sequences can be useful in fields such as computer programming, where patterns and sequences are often used in algorithms and coding.

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