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Answer: $-1$
Let $2016$ or $2017$ be $n$, the calculation is $(n-1)×(n+1) - n^2$
For any $n$, $(n-1)×(n+1) = n^2+n-n-1 = n^2-1$
So $(n-1)×(n+1) - n^2 = n^2-1-n^2=-1$
Little Difference
Age 14 to 16
ShortChallenge Level 
Answer: $-1$
Let $2016$ or $2017$ be $n$, the calculation is $(n-1)×(n+1) - n^2$
For any $n$, $(n-1)×(n+1) = n^2+n-n-1 = n^2-1$
So $(n-1)×(n+1) - n^2 = n^2-1-n^2=-1$
This problem is taken from the UKMT Mathematical Challenges.
You can find more short problems, arranged by curriculum topic, in our short problems collection.
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