Like 8 × 8 = 64, 7 × 9 = 63, 25 × 25 = 625, 24 × 26 = 624, what rules do you find Narrate with language and express the law of this with algebraic formula

Like 8 × 8 = 64, 7 × 9 = 63, 25 × 25 = 625, 24 × 26 = 624, what rules do you find Narrate with language and express the law of this with algebraic formula

(a-1)*(a+1)=a*a-1