1. Calculer : (6 x 6) - (5 x 5) + (4 x 4) - (3 x 3) =

2. (9 x 9) - (8 x 8) - (7 x 7) + (6 x 6) =

3. (12 x 12) - (11 x 11) - (10 x 10) + (8 x 8) =

4. (15 x 15) - (13 x 13) + (5 x 5) - (9 x 9) =

5. (18 x 18) - (11 x 11) + (17 x 17) - (7 x 7) =

6. (11 x 19) + (12 x 20) - (13 x 21) =