A given integer can be written in how many different ways?

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In summary: So they are not so old.it mentions that Ken Iverson introduced the actual names when he developed APL in the 1960s. So they are not so old.In summary, the conversation involves finding the number of ways to express 24 as a sum of two integers ranging from 1 to 24. The participants discuss different methods and eventually settle on using a table to find the answer. They also discuss the use of the floor function and its origins in computer programming.
  • #1
kent davidge
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I had learned how to find this out in the past, but forgot now. Precisely, I'm trying to find in how many different ways I can express the number 24 as a sum of two integers ranging from 1 to 24. For example, 24 = 24 = 23 + 1 = 12 + 12...
 
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  • #2
Do you count (23,1) and (1,23) as two or one?
 
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  • #3
Just make a little table. First column is 0,1,...;second column is 24,23,...
Then it should be clear when you get to 13...?
 
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  • #4
fresh_42 said:
Do you count (23,1) and (1,23) as two or one?
One. This somehow hints me at the usage of permutations.
 
  • #5
With two objects its not a big deal...its either forward or backward
 
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  • #6
Going through permutations, perhaps it is better to start off with a smaller number to get a feeling of what I'm working with. Let me take number 4. I can form ##4!/(2!2!)## pairs composed of two different numbers from the set ##\{1,2,3,4\}##, right? This is equal to 6. However this is still bigger than the actual number, which I did by hand and is 4, i.e., 4 = 4 = 3 + 1 = 2 + 2 + 2 = 2 + 1 + 1. That must be because in the calculation I did, I included 3 + 3 and 4 + 4. So I would have to figure out a way of removing those combinations that sum up to a number greater than the number I'm considering.

So I'm not sure this method is useful.
 
  • #7
Try the table described in post #3. This is not difficult.
 
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  • #8
hutchphd said:
Try the table described in post #3. This is not difficult.
aha, indeed it gives me the number of ways "right on the nose" as you english speakers say :)
 
  • #9
kent davidge said:
aha, indeed it gives me the number of ways "right on the nose" as you english speakers say :)
The most difficult thing is the floor function: ##\lfloor \frac{n}{2} \rfloor##.
 
  • #10
fresh_42 said:
The most difficult thing is the floor function
I am an old guy and I never heard that nomenclature (floor) until maybe a year ago. Did it migrate from a particular computer language?? It is less ambiguous.
 
  • #11
I think floor and ceil are older than programming, but I have no idea where it first appeared. Probably quite a while ago, because they simply generalize the (Gauß?) bracket ##[r]## for the nearest integer.
 
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1. What is the meaning of "a given integer can be written in how many different ways?"

The phrase "a given integer can be written in how many different ways" refers to the number of unique combinations or arrangements of numbers that can be used to represent a specific integer. This can include different orders, groupings, or operations.

2. How do you determine the number of ways an integer can be written?

The number of ways an integer can be written can be determined by using mathematical principles such as permutation and combination. It involves analyzing the given integer and identifying the different ways it can be represented using mathematical operations.

3. Is there a limit to the number of ways an integer can be written?

Yes, there is a limit to the number of ways an integer can be written. The limit depends on the size of the integer and the mathematical operations that are allowed. As the integer gets larger, the number of possible ways to write it also increases.

4. Can an integer be written in an infinite number of ways?

No, an integer cannot be written in an infinite number of ways. As mentioned before, there is a limit to the number of ways an integer can be written. Even if the integer is extremely large, there will still be a finite number of ways to represent it.

5. How does the order of numbers affect the number of ways an integer can be written?

The order of numbers can greatly affect the number of ways an integer can be written. For example, the numbers 1, 2, and 3 can be arranged in 6 different ways (123, 132, 213, 231, 312, 321), but if the order is changed (e.g. 1, 3, 2), the number of ways will also change. This is why permutation is an important concept in determining the number of ways an integer can be written.

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