能用简便方法的要用简便方法计算 2/5×10+10×3/5 4.86×[1÷(2.1-2.09)] 8.8-6.75+9.2-0.25 99999+9999+999+99+9+6.

问题描述:

能用简便方法的要用简便方法计算

2
5
×10+10×
3
5

4.86×[1÷(2.1-2.09)]
8.8-6.75+9.2-0.25              
99999+9999+999+99+9+6.

2
5
×10+10×
3
5

=10×(
2
5
+
3
5

=10×1
=10
②4.86×[1÷(2.1-2.09)]
=4.86×(1÷0.01)
=4.86×100
=486
③8.8-6.75+9.2-0.25
=(8.8+9.2)-(6.75+0.25)
=18-7
=11
              
④99999+9999+999+99+9+6
=(99999+1)+(9999+1)+(999+1)+(99+1)+(9+1)+1
=100000+10000+1000+100+10+1
=111111