13.9×9.9+1.39
=13.9×9.9+13.9×0.1
=13.9×(9.9+0.1)
=13.9×10
=139
13.9*9.9+1.39=1.39*(99+1)=1.39*100=139
13.9*9.9+1.39怎样简便计算
13.9*9.9+1.39
=13.9×99+13.9×0.1
=13.9×(9.9+0.1)
=13.9×10
=139
13.9*(9.9+0.1)=139
13.9*9.9+1.39
=13.9×9.9+13.9×0.1
=13.9×(9.9+0.1)
=13.9×10
=139
等于4 没有简算
13.9*101-10*1.39
=13.9*101-13.9
=13.9*(101-1)
=13.9*100
=1390
解:原式=13.9x9.9+0.01x139
=13.9x9.9+13.9x0.1
=13.9x(9.9+0.1)
=13.9x10
=139
分析:主要考察提取公因式的运用。
13.9×0.98
=(14-0.1)×(1-0.02)
=14×1-14×0.02-0.1×1+0.1×0.02
=14-0.28-0.1+0.002
=14-0.378
=13.622
13.9+21.7+35.1
=(13.9+35.1)+21.7
=49+21.7
=70.7
谢谢,请采纳