题目内容
30+20=
[ ]
A.0
B.50
C.70
选数填空.
40,50,60,70,800,30,20,90,80,420,1,10
( )×( )=800 ( )×( )=2800
( )×( )=4200 ( )×( )=3600
( )×( )=1500 ( )×( )=1800
( )×( )=2100 ( )×( )=64000
口算.
70-30-20= 69-9+30= 3+4+50=
350÷50= 100÷20= 540÷90=
640÷80= 720÷90= 450÷30=
120÷20= 210÷30= 240÷80=
420÷70= 360÷60= 160÷80=
1500÷30= 2000÷50= 3600÷30=