Some Math / Number Theory Tricks

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2#  A number N can be represented by the difference of the square of two numbers that means it is possible to find two integers p and q such that 
N = p^2 - q^2

If

N is Odd or N is divisible by 4.
        If we named this type of number is a good number then
     2.1# If two number A and B both are good number then the product of them are also must be a good number

3# If a array / sequence have N element then total number of subarray / contigious_subsequence is n(n+1)/2
















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