简便运算急1999×999×9991.25×0.737×0.125×3.63-0.125以上两题必须用简便算法如果能说出所用到得运算律更好

Question

简便运算 急
1999×999×999 1.25×0.737×0.125×3.63-0.125
以上两题必须用简便算法 如果能说出所用到得运算律更好

Answer 1

写错了吧
应该是
1999×999+999
=(1999+1)×999
=2000×999
=1998000
1.25×0.737+0.125×3.63-0.125
=0.125×10×0.737+0.125×3.63-0.125
=0.125×7.37+0.125×3.63-0.125
=0.125×(7.37+3.63-1)
=0.125×10
=1.25