Question

7.81×3.1+6.9×4.29+3.52×6.9的简便计算是什么？

Answer 1

解：7.81X3.1+6.9X4.29+3.52X6.9=7.81X3.1+6.9X（4.29+3.52）=7.81X3.1+6.9X7.81=7.81X（3.1+6.9）=7.81X10=78.1

Answer 2

观察这道题的后面的两个乘法算式中有相同的数6.9，符合乘法分配律，计算后和前面的乘法算式中又有相同的数7.81，再次符合乘法分配律，所以经过两次计算后就简便了。过程如下：
7.81×3.1+6.9×4.29+3.52×6.9
=7.81×3.1+6.9×（4.29+3.52）
=7.81×3.1+6.9×7.81
=7.81×（3.1+6.9）
=7.81×10
=78.1

Answer 3

原式=7.81×3.1+6.9×（4.29+3.52）=7.81×3.1+6.9×7.81=7.81×（3.1+6.9）=7.81×10=78.1

Answer 4

7.81×3.1+6.9×4.29+3.52×6.9
＝7.81×3.1+6.9×（4.29+3.52）
＝7.81×3.1+6.9×7.81
＝7.81×（3.1+6.9）
＝7.81×10
＝78.1

Answer 5

=7.81×3.1+（4.29+3.52）×6.9
=7.81×3.1+7.81×6.9
=（3.1+6.9）×7.81
=10×7.81
=78.1