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一、下面的算式分别运用了哪种运算律？请在表格中相应的位置画“√”。
答案
|算式|加法交换律|加法结合律|
| ---- | ---- | ---- |
|$5.3+3.4=3.4+5.3$|√| |
|$5.6+0.88+4.4=5.6+4.4+0.88$|√| |
|$12+8.9+11.1=12+(8.9+11.1)$| |√|
|$3.3+5.44+0.56+6.7=(3.3+6.7)+(5.44+0.56)$|√|√|
| ---- | ---- | ---- |
|$5.3+3.4=3.4+5.3$|√| |
|$5.6+0.88+4.4=5.6+4.4+0.88$|√| |
|$12+8.9+11.1=12+(8.9+11.1)$| |√|
|$3.3+5.44+0.56+6.7=(3.3+6.7)+(5.44+0.56)$|√|√|
二、在横线上填上适当的数。
$18.6+4.7+1.4=18.6+$
$12.64+0.63+0.37=12.64+$
$48.72-0.2-0.8=48.72-$
$195.4-12.9-87.1=195.4-$
$18.6+4.7+1.4=18.6+$
1.4
$+4.7$$12.64+0.63+0.37=12.64+$
0.63
$+$0.37
$48.72-0.2-0.8=48.72-$
0.2
$+$0.8
$195.4-12.9-87.1=195.4-$
12.9
$+$87.1
答案
1.4 0.63 0.37 0.2 0.8 12.9 87.1
三、计算下面各题，怎样简便就怎样计算。
$7.29+1.54+2.71$ $9.85-4.3-1.7$ $1.25+2.36+4.64$
$7.29+1.54+2.71$ $9.85-4.3-1.7$ $1.25+2.36+4.64$
答案
11.54 3.85 8.25
