# Math puzzle: combinations of digits

• Logger
In summary, there are 78 possible combinations that can be made from the 5 numbers given, but the correct answer is 31.
Logger
OP warned about not using the homework template
My 10 year old daughter was given this maths puzzle and I'm sure to you guys it would be pretty easy.

You have 5 numbers 1,2,3,4,5

Ho many possible combinations are there possibe for 1 digit combos,2 digit combos, 3 digit combos, 4 digit combos, and 5 digit combos. The numbers cannot repeat at any time and you cannot have the reverse of the numbers also (e.g 345 and 543 as same 3 numbers used in this 3 digit combo.)

For single digit combos there is onviously only 5 combos 1-5 (5)
For 5 digit combos there is only one combination 1-5 (1) as any other combo still uses the same 5 numbers
I thought using 5*4*3*2*1 / 4+3+2+1 = (12) would be the correct answer for the 4 digit combos
and that 5*4*3*2*1 / 3 +2 +1 = (20) would be correct for 3 digit combos and that 5*4*3*2*1 / 2+1 = (40) for 2 digit combos.

So total combos 5 + 40 + 20 + 12 + 1 = 78 possible combos would be correct but it's not.

What is the correct answer and can you explain how it is done.

Thanks in advance

She should start by listing all possibilities for 2 digits (including reversals), then excluding reversals, and try to deduce a pattern from that.

Logger said:
My 10 year old daughter was given this maths puzzle and I'm sure to you guys it would be pretty easy.

You have 5 numbers 1,2,3,4,5

Ho many possible combinations are there possibe for 1 digit combos,2 digit combos, 3 digit combos, 4 digit combos, and 5 digit combos. The numbers cannot repeat at any time and you cannot have the reverse of the numbers also (e.g 345 and 543 as same 3 numbers used in this 3 digit combo.)

For single digit combos there is onviously only 5 combos 1-5 (5)
For 5 digit combos there is only one combination 1-5 (1) as any other combo still uses the same 5 numbers
I thought using 5*4*3*2*1 / 4+3+2+1 = (12) would be the correct answer for the 4 digit combos
and that 5*4*3*2*1 / 3 +2 +1 = (20) would be correct for 3 digit combos and that 5*4*3*2*1 / 2+1 = (40) for 2 digit combos.

So total combos 5 + 40 + 20 + 12 + 1 = 78 possible combos would be correct but it's not.

What is the correct answer and can you explain how it is done.

Thanks in advance

For 4-digit combos, every combo is defined by the number missing. So, there are not 12 of those.

Logger said:
Somebody sent me the answer...31
You really think your daughter should only care about the numerical answer?

The link that I included on my previous post showed the formula and how it works and the proof. Do you really think a maths teacher would allow a child just come up with a numerical answer anyway? Thanks for taking the time to reply.Take care.

## What is a math puzzle involving combinations of digits?

A math puzzle involving combinations of digits is a type of problem that requires you to arrange a set of numbers in a specific way to solve it. These puzzles often involve using addition, subtraction, multiplication, division, and other mathematical operations to find the solution.

## How do I solve a math puzzle involving combinations of digits?

To solve a math puzzle involving combinations of digits, you need to carefully analyze the given numbers and their relationships. It is helpful to write down the numbers and use different operations to manipulate them until you reach the desired result. It may also be helpful to try different combinations and keep track of your progress.

## Can math puzzles involving combinations of digits have more than one solution?

Yes, some math puzzles involving combinations of digits can have multiple solutions. It depends on the specific puzzle and the given numbers. Some puzzles may have only one correct solution, while others may have multiple possibilities.

## Are there any strategies for solving math puzzles involving combinations of digits?

There are various strategies that can be used to solve math puzzles involving combinations of digits. One approach is to work backward from the desired result, while another is to break down the problem into smaller parts and solve them individually. It is also helpful to use logic and pattern recognition to identify relationships between the numbers.

## Can math puzzles involving combinations of digits help improve mathematical skills?

Yes, solving math puzzles involving combinations of digits can help improve mathematical skills such as problem-solving, critical thinking, and number manipulation. These puzzles often require a combination of mathematical knowledge and creative thinking, making them a great way to practice and develop these skills.

Replies
11
Views
1K
Replies
6
Views
956
Replies
1
Views
1K
Replies
23
Views
1K
Replies
1
Views
876
Replies
1
Views
822
Replies
7
Views
1K
Replies
20
Views
2K
Replies
11
Views
2K
Replies
4
Views
1K