1. Diagonal formula
|12 -7; 4 9|: 12x9 - (-7)x4 = 136.
2x2 mastery (+/-15)
1 visual step / 2x2 diagonal difference
Practice Level 6
A few quick rounds make the products familiar; the sign is the only thing to guard.
Start Level1 visual step / 2x2 diagonal difference
|12 -7; 4 9|: 12x9 - (-7)x4 = 136.
A few quick rounds make the products familiar; the sign is the only thing to guard.
Start Level