你能想出简便方法来计算下面各题吗?(12’)25×5+74×5+5 6.74+12.62+24.38+3.2687-2.123-0.877 30.65-(7.65+5.4)
口算(1)8+6= (2)9+9= (3)15-6= (4)8+6=(5)9-5= (6)7+8= (7)13-8= (8)12-8=(9)17-8= (10)13-5= (11)6-3= (12)11-2= (13)14-5= (14)11-3= (15)13-10= (16)12-9=(17)12-3= (18)15-7= (19)12-6= (20)14-3=
计算.5+1+3= 5-3+6=9-6-2= 9-6+7=9-7-2= 6+3-7=7+2-5= 2+5-4=8-3-0= 4-2+5=9-8-1= 10-4+l=
计算下面各题.2+5= 9-4= 7+3=6-4= 2+2= 6-6=1+5= 7-5= 8-7=2+8= 4+5= 9-6=8-4= 8-2= 8+1=4+6= 10-9= 10-4=
口算.5+4= 5-3= 3+0=8+7= 9+7= 7-7=3+5= 10-4= 9-8=7-2= 7-6= 3+7=10-6= 9-6= 9-5=5-4= 8-3= 5+2=
比一比,看谁做得又对又快!2+3= 6-3= 7-4=4+2= 3+3= 4+5=5-2= 6-5= 3+4=6+l= 8-5= 2+4=8-4= 5-4= 7-3=