Question 416857
n & n+2 are the numbers
{{{(n+2)^2 - n^2 = n^2 + 2n + 4 - n^2 = 2n + 4}}}
2*(n + n+2) = 2n+4
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It's true for odd or even numbers, as shown above.
The difference between the squares is the difference between the numbers times the sum of the numbers.
Diff of squares = (Diff of numbers) * (sum of numbers)
There's no good reason to try to remember that, imo.