Question

用简便方法计算。

(1)12.8－4.9－5.1	(2)6.75－(0.9＋3.75)
(3)1.34＋1.8+3.66＋0.2	(4)0.96－0.28＋0.04－0.72

                                                       

Answer 1

(1)   12.8-4.9-5.1      =12.8-(4.9+5.1)      =12.8-10      =2.8	(2)  6.75-（0.9+3.75）     =6.75-3.75-0.9     =3-0.9     =2.1
(3)   1.34+1.8+3.66+0.2      =(1.34+3.66)+(1.8+0.2)      =5+2      =7	(4)   0.96-0.28+0.04-0.72      =0.96+0.04-(0.28+0.72)      =1-1      =0