The given statement can be written in five different ways as follows.(i) A natural number is odd implies that its square is odd.(ii) A natural number is odd only if its square is odd.(iii) For a natural number to be odd, it is necessary that its square is odd.(iv) For the square of a natural number to be odd, it is sufficient that the number is odd.(v) If the square of a natural number is not odd, then the natural number is not odd.