Exercice 7:
712 =
700 + 10 + 2
400 + 40 + 2 =
442
769 =
900 + 30 + 1 =
789 =
400 + 50 + 5 =
207 =
600 + 50 + 5 =
456 =
100 + 20 + 2 =
