a)7×5-7×3=7(5-3)=7×2=14
b)2×3+3×8-3=3(2+8-1)=3×9=27
c)15+15-7=15(1+1)-7=15×2-7=30-7=23
d)7×9-7=7(9-1)=7×8=56
e)143×81+143×11+143×7+143=143(81+11+7+1)=143×100=14300
exercițiul de mai jos
a)3×8+3×2=3(8+2)=3×10=30
b)7×103-7×3=7(103-3)7×100=700
c)136×17+136×83=136(17+83)=136×100=13600
d)42×705+58×705=705(42+58)=705×100=70500
e)2653×347+2653×696-43-2653=2653(347+696-43)=2653×1000=2653000
f)99999×8-99999×2=99999(8-2)=99999×6=599994
g)3745×99+3745=3745×100=374500
h)49506×101-49506=49506(101-1)=49506×100=4950600
i)145×8+145×12+145×30=145(8+12+30)=145×50=7250
