Răspuns :
a+b+c+d
a=639
b=639:3=213
c=639+213=852
d=852x6=5211
le punem intr-un singur exercitiu
639+(639:3)+(639+639:3)+[(639+639:3)x6]=
639+213+(639+213)+[(639+213)x6]=
639+213+852+(852x6)=
1704+5211=6816
a=639
b=639:3=213
c=639+213=852
d=852x6=5211
le punem intr-un singur exercitiu
639+(639:3)+(639+639:3)+[(639+639:3)x6]=
639+213+(639+213)+[(639+213)x6]=
639+213+852+(852x6)=
1704+5211=6816