Question d’entretien chez Jane Street
49x51=?
Réponse à la question d'entretien
Utilisateur anonyme
8 déc. 2015
obviously its easy with a calculator but you're not meant to have one at hand so what you do here for quick mental arithmetic is difference of 2 squares 49x51=(50-1)x(50+1)=50x50-1=2500-1=2499