Question

(6.9+2.1÷0.15)÷0.2的简便计算？

Answer 1

(6.9+2.1÷0.15)÷0.2

=(6.9+210÷15)÷2/10......(2.1÷0.15=(2.1×100)÷(0.15×100)=210÷15, 0.2=2/10）

=(6.9+7×30÷15)×10/2........（除以一个数，等于乘以这个数的倒数）

=(6.9+14)×5

=20.9×5

=20×5+0.9×5。。。。（乘法分配律）

=100+4.5

=104.5

Answer 2

(6.9+ 2.1÷0.15)÷2/10
=（6.9+14）*5
=6.9*5+14*5乘法分配律。简便计算
=34.5+70
=104.5

Answer 3

6.9十2.1÷0.2÷0.15＝6.9十1.05÷0.15＝6.9十7＝13.9