Răspuns:
a)7×99=7×(100-1)=7×100-7×1=700-6=694
b)4×6001=4×(6000+1)=4×6000+4×1=24000+4
=24004
c)7+631=7×(600+30+1)=7×600+30+1×30+7×1=4417
a)8×98=8×(100-2)=8×100-8×2=800-16=784
b)9×8003=9×(8000+3)=9×8000+9×3=72000-27
=71973
c)5×498=5×(500-2)=5×500-2×5=2500-10=2490
