1.Tính nhanh
a)427-98
b)2*19*15+3*43*10+62*80
c)\(\frac{1}{3}+\frac{1}{9}+\frac{1}{27}+\frac{1}{81}+\frac{1}{243}+\frac{1}{729}\)
d)\(\left(1-\frac{1}{9}\right)\cdot\left(1-\frac{2}{9}\right)\cdot\left(1-\frac{3}{90}\right)\cdot.........\cdot\left(1-\frac{2018}{9}\right)\)