Question

递等式（能巧算就巧算）①26×20.2-8.4-1.8 ②（3.2×0.4-0.68）÷0.25×4

过程、格式清楚点，一行一行

Answer 1

1. 26×20.2-8.4-1.8=26×20.2-10.2=25×20.2+(10.2-10.2)=25×20+25×0.2=500+5=505

2.②（3.2×0.4-0.68）÷0.25×4=(3.2×0.4-0.68)×4×4=(1.28-0.68)×16=0.6×16=0.96

Answer 2

① 26×20.2-8.4-1.8
= 26 X 2 X 10.1 -（8.4 + 1.8）
= 52 X 10.1 - 10.2
= 52.52- 10.2
= 42.32

②（3.2×0.4 - 0.68）÷0.25 × 4
=（3.2×0.4 - 0.68）÷（1/4）× 4
=（3.2×0.4 - 0.68）× 4 × 4
=（1.28 - 0.68）× 4 × 4
= 0.6 X 16
= 9.6

Answer 3

（1）515
（2）9.6