2.8x0.5+1.58简便运算

2.8 × 0.5 + 1.58
= 1.4 + 1.58
= 1.4 + 1.6 - 0.02
= 3 - 0.02
= 2.98

2.8x0.5+1.58
=1.4+1.58
=2.98

2.8x0.5+1.58=2.8x1/2+1.6=1.4+1.6=3