Consecutive Integers: Sums and Products
Consecutive integers form arithmetic sequences with d=1. Sum = n ร (first+last)/2. To find integers summing to S: solve for the first term. Even/odd consecutive use d=2.
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Gauss summed 1 to 100 as a child: 100ร101/2 = 5050. Consecutive evens: 2, 4, 6...; odds: 1, 3, 5... Product of n consecutive is divisible by n!.
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Why: Consecutive integer problems appear in puzzles, algebra, and number theory. Given a target sum, find the sequence. Gauss formula gives 1+2+...+n = n(n+1)/2.
How: For sum of n consecutive: if first = a, sum = nรa + n(n-1)/2. Set equal to target, solve for a. For product, use factorial or iterative search.
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๐ Step-by-Step Breakdown
For educational and informational purposes only. Verify with a qualified professional.
๐งฎ Fascinating Math Facts
Sum of first n naturals = n(n+1)/2 โ Gauss formula.
Product of n consecutive integers is divisible by n!.
๐ Key Takeaways
- โข Sum of n consecutive integers: n ร (first + last) / 2
- โข Powers of 2 cannot be written as sums of consecutive integers
- โข Consecutive even/odd: same formula with step 2 instead of 1
๐ก Did You Know?
๐ How It Works
For sum = n ร (first + last) / 2, we solve for first given sum and n. For consecutive integers, last = first + n - 1, so first = (2รsum/n - n + 1) / 2. For even/odd consecutive, the step between terms is 2.
๐ Worked Example: 15
Sets summing to 15:
1+2+3+4+5 = 15
4+5+6 = 15
7+8 = 15
๐ฏ Expert Tips
- Check if 2รsum is divisible by n to quickly filter candidates
- For odd n, the middle term equals the average (sum/n)
- Powers of 2 have no representation as sum of consecutive integers
โ FAQ
What are consecutive integers?
Whole numbers that follow each other: n, n+1, n+2, ...
Can any number be a sum of consecutive integers?
No. Powers of 2 cannot. All others can.
What is the sum of 1 to n?
n(n+1)/2. For n=100: 5050.
How to find consecutive integers with a given sum?
Solve first = (2รsum/n - n + 1)/2 for each n; first must be integer.
What about consecutive even or odd?
Same idea with step 2: first, first+2, first+4, ...
โ ๏ธ Disclaimer: Results are for educational purposes. Verify critical calculations independently.
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