prove that the square of any positive integer is of form 4w , 4w+1 , 4w+2 or 4w+3 for ssome integer w.
let the positive integer be 4p, 4p+1, 4p+2
If n= 4p
n2=16p2
=4(4p2)
=4w
Similarly,
If n= 4p+1
n2=(4p+1)2
=16p2+8p+1
= 4(4p2+4p)+1
=4w+1
If n=4p+2
n2=(4p+2)2
=16p2+16p+4
=4(4p2+4p+1)
=4w
Hence proved.