Let \(N=2^k\times4^m\times8^n\)where \(k,m,n\) are positive whole numbers. Then \(N\) will definitely be a square number whenever
\(k\) is even;
\(k+n\) is odd;
\(k\) is odd but \(m+n\) is even;
\(k+n\) is even.
When is a number a square? How else can we write the factors to help us?