计算
$1.8 - 0.9 =$
$0.4 + 0.8 =$
$4.7 - 1.9 =$
$0.35 + 0.45 =$
$1.5 + 2.3 =$
$8.5 - 4.2 =$
$1.3 + 0.7 =$
$6.4 - 3.9 =$
$0.8 + 1.2 =$
$9.9 + 1 =$
$3 + 4.6 =$
$7 - 3.9 =$
$2.5 × 3 =$
$0.6 × 0.9 =$
$0.8 × 0.3 =$
$3.5 × 0.2 =$
$0.15 × 4 =$
$4 × 0.25 =$
$0.4 × 1.2 =$
$5.5 × 0.2 =$
$0.3 × 0.6 =$
$2.5 × 0.6 =$
$3.3 × 4 =$
$6 × 1.4 =$
$8 × 0.5 =$
$0.8 × 0.5 =$
$2.5 × 4 =$
$2.5 × 0.4 =$
$24 × 5 =$
$2.4 × 0.5 =$
$25 × 8 =$
$2.5 × 0.8 =$
$1.4 × 5 =$
$1.4 × 0.5 =$
$6 × 7 =$
$0.6 × 0.7 =$

$1.8 - 0.9 = 0.9$
$0.4 + 0.8 = 1.2$
$4.7 - 1.9 = 2.8$
$0.35 + 0.45 = 0.8$
$1.5 + 2.3 = 3.8$
$8.5 - 4.2 = 4.3$
$1.3 + 0.7 = 2$
$6.4 - 3.9 = 2.5$
$0.8 + 1.2 = 2$
$9.9 + 1 = 10.9$
$3 + 4.6 = 7.6$
$7 - 3.9 = 3.1$
$2.5 × 3 = 7.5$
$0.6 × 0.9 = 0.54$
$0.8 × 0.3 = 0.24$
$3.5 × 0.2 = 0.7$
$0.15 × 4 = 0.6$
$4 × 0.25 = 1$
$0.4 × 1.2 = 0.48$
$5.5 × 0.2 = 1.1$
$0.3 × 0.6 = 0.18$
$2.5 × 0.6 = 1.5$
$3.3 × 4 = 13.2$
$6 × 1.4 = 8.4$
$8 × 0.5 = 4$
$0.8 × 0.5 = 0.4$
$2.5 × 4 = 10$
$2.5 × 0.4 = 1$
$24 × 5 = 120$
$2.4 × 0.5 = 1.2$
$25 × 8 = 200$
$2.5 × 0.8 = 2$
$1.4 × 5 = 7$
$1.4 × 0.5 = 0.7$
$6 × 7 = 42$
$0.6 × 0.7 = 0.42$

怎样简便就怎样计算
$1.25×0.9×8$
$7.2×3.5+3.5×2.8$
$7.5+2.5×5$
$25×(4+0.4)$
$25.4-(5.4+8.2)$
$5.4×101-5.4$

$1.25×0.9×8$
$=1.25×8×0.9$
$=10×0.9$
$=9$
$7.2×3.5+3.5×2.8$
$=3.5×(7.2+2.8)$
$=3.5×10$
$=35$
$7.5+2.5×5$
$=7.5+12.5$
$=20$
$25×(4+0.4)$
$=25×4+25×0.4$
$=100+10$
$=110$
$25.4-(5.4+8.2)$
$=25.4-5.4-8.2$
$=20-8.2$
$=11.8$
$5.4×101-5.4$
$=5.4×(101-1)$
$=5.4×100$
$=540$