Răspuns :
a)35×99=35×(100-1)=35×100-35×1
=3500-35=3465
b)27×101=27×(100+1)=27×100+27×1
=2700+27=2727
c)15×102=15×(100+2)=15×100+15×2
=1500+30=1530
d)31×98=31×(100-2)=31×100-31×2
=3100-62=3038
e)4×999=4×(1000-1)=4×1000-4×1
=4000-4=3996
f)5×1004=5×(1000+4)=5×1000+5×4
=5000+20=5020
=3500-35=3465
b)27×101=27×(100+1)=27×100+27×1
=2700+27=2727
c)15×102=15×(100+2)=15×100+15×2
=1500+30=1530
d)31×98=31×(100-2)=31×100-31×2
=3100-62=3038
e)4×999=4×(1000-1)=4×1000-4×1
=4000-4=3996
f)5×1004=5×(1000+4)=5×1000+5×4
=5000+20=5020
a) 35 × 99 = 35 × ( 100 - 1 ) = 35 × 100 - 35 × 1 = 3 500 - 35 = 3 465
b) 27 × 101 = 27 × ( 100 + 1 ) = 27 × 100 + 27 × 1 = 2 700 + 27 = 2 727
c) 15 × 102 = 15 × ( 100 + 2 ) = 15 × 100 + 15 × 2 = 1 500 + 30 = 1 530
d) 31 × 98 = 31 × ( 100 - 2 ) = 31 × 100 - 31 × 2 = 3 100 - 62 = 3 038
e) 4 × 999 = 4 × ( 1 000 - 1 ) = 4 × 1000 - 4 × 1 = 4 000 - 4 = 3 996
f) 5 × 1 004 = 5 × ( 1 000 + 4 ) = 5 × 1000 + 5 × 4 = 5 000 + 20 = 5 020