数学简便运算

19.9*3.56+199*0.644
=199*0.356+199*0.644
=199*(0.356+0.644)
=199*1
=199

1.1*1.1*9+1.1*1.1-10
=1.1*1.1*(9+1)-10
=1.1*1.1*10-10
=(1.1*1.1-1)*10
=0.21*10
=2.1

1
19.9*(3.56+6.44)=199
2
1.1*1.1*8-10
1.21*8-10
9.68-10
-0.32

1.解:原式=19.9*3.56+19.9*6.44
=19.9*(3.56+6.44)
=19.9*10
=199
2.好象没有简便方法
你可能打错了

1
原式=199*0.356+199*.644=199*(0.356+.644)=199

2
原式=1.1*1.1*(9+1)-10=1.1*1.1*10-10=11*1.1-11+1=11*(1.1-1)+1=2.1