1) 201,8 . 3,4 - 0,9 . 6,8
=. 686,12. -6,12
=680
3) 2,020/0,125+2,020/0,5
=2,020/(0,125/0,5)
=2,020/0,25
=8,08
4)20,21*6,8+20,21*31+20,21
=20,21*6,8+20,21*31+20,21*1
=20,21(6,8+31+1)
20,21*38,8
=784,148
5)2,005*1004-8,02
=2013,08,02
=2005
Mk chỉ lm đc. 4 câu thui nhé