Question

7.8x1.3+8.7怎么简便运算

Answer 1

7.8×1.3+8.7

=7.8×（10-8.7）+8.7

=78-7.8×8.7+8.7

=7.8×10-7.8×8.7+8.7

=78-8.7×（7.8-1）

=78-8.7×6.8

=18.84

Answer 2

回答：
7.8×1.3+8.7
=（8-0.2）×1.3+8.7
=8×1.3-0.2×1.3+8.7
=10.4-0.26+8.7
=10.14+8.7
=18.88
运用了乘法分配律