Calculează :
a) 4+4+4+4+4=8+[]+[]+[]=12+[]+[]+[]+[]+[]
b)9+9+9+9=18+[]+[]=[]+[]=[]
c)6+6+6+6+6+6=[]+[]+[]+[]+[]=[]+[]+[]+[]=[]+[]+[]=[]+[]=[]​