Remember: Any number k when divided by 4will be in the form of 4k,4k+1,4k+2 and 4k+3 Here squares of 1, 2 and 3 are 1, 4 and 9, respectively, which is in the form of 4k or 4k+1 For example 4=4×1, which is of the form 4k 16=4×4, which is of the form 4k 9=4×2+1, which is of the form 4k+1 25=4×6+1, which is of the form4k + 1 Therefore, every square integer is of the form 4k or 4k+1.