我想知0.39 x 39 + 6.1 x 3.9 的簡易方法

因0.39*39=3.9*3.9
即0.39 x 39 + 6.1 x 3.9
=3.9*3.9+6.1*3.9
=3.9*(3.9+6.1)
=3.9*10
=39

0.39x39+61x3.9

=39x39x61x39

0.39x 39 + 6.1 x 3.9
=3.9x3.9+ 6.1 x 3.9
=(3.9+6.1)x3.9
=10x3.9
=39

0.39 x 39 + 6.1 x 3.9
=15.21+ 6.1 x 3.9
=15.21+23.79
=39

0.39 x 39 + 6.1 x 3.9
=3.9x3.9+6.1x3.9
=3.9(3.9+6.1)
=3.9x10
=39


或

0.39x39+6.1x3.9
=0.39x39+61x0.39
=0.39(39+61)
=0.39x100
=39


或
　
0.39x39+6.1x3.9
=0.39x39+0.61x39
=39(0.39+0.61)
=39x1
=39

非常易
睇住啦

0.39*39+6.1*3.9
呢條數好簡單姐
你把3.9除以10
再把6.1乘以10
明唔明
未明?
唔緊要
簡單d黎講
姐係6.1*3.9係一個縮小若干
另一擴大若干

條數係咁計
0.39*39+6.1*3.9
=0.39*39+61*0.39
乘法分配律學左未

=0.39*(39+61)
=0.39*100
=39



完整d:
0.39*39+6.1*3.9
=0.39*39+61*0.39
=0.39*(39+61)
=0.39*100
=39

0.39 x 39 + 6.1 x 3.9

= 3.9 X 3.9 + 6.1 X 3.9 [ 即係前面的0.39除了10, 後面的39除番10就平衡返]

= 3.9 X (3.9 + 6.1)

= 3.9 X 10

= 39