一、口算。
$72+36=$
$4.6+2.1=$
$23×4=$
$83-28=$
$7.3-1.6=$
$256+42=$
$322×2=$
$242÷2=$
$60×30=$
$609÷3=$
$140×6=$
$5+9.68=$
$5.13-3.4=$
$480÷40=$
$0.43-0.08=$
$65×20=$
$357÷3=$
$150×40=$
$101×50=$
$13×700=$
$8100÷3=$
$0.18+0.81=$
$850÷17=$
$8000÷400=$

72+36=108
4.6+2.1=6.7
23×4=92
83-28=55
7.3-1.6=5.7
256+42=298
322×2=644
242÷2=121
60×30=1800
609÷3=203
140×6=840
5+9.68=14.68
5.13-3.4=1.73
480÷40=12
0.43-0.08=0.35
65×20=1300
357÷3=119
150×40=6000
101×50=5050
13×700=9100
8100÷3=2700
0.18+0.81=0.99
850÷17=50
8000÷400=20

二、计算下面各题，怎样简便就怎样计算。
1. $34 + 3.87 + 5.2$
$408 ÷ 8 + 49 × 51$
$1090 - 90 ÷ 5 × 2$
$156 × 101 - 156$
$25 × (4 + 8) × 125$
$285 ÷ (154 - 9 × 15)$

1. 34 + 3.87 + 5.2 = 10.41
408 ÷ 8 + 49 × 51 = 2550
1090 - 90 ÷ 5 × 2 = 1054
156 × 101 - 156 = 15600
25 × (4 + 8) × 125 = 37500
285 ÷ (154 - 9 × 15) = 15