四年级数学口算题9-3=90-3=900-3=70x20=180-2=4000-5=360-6=1400-7=200-5=720-8=27-9=270-9=30x60=300-6=150-5=490-7=90x4=90-3=90x70=42-6x6=24-4=240-4=90x9=8100-9=300-5=420-7=720-9=20x21=300-6=140-2=700x8=350-5=5x6+41=1600-4=2700-9=4000-8=360-6=1400-2=200-4=720-9=78-4=83-9=470-8=178-6=83-9=360-5=410-7=125-2=21-4=71-9=900+700=90+80=90+9=12-6=200-60=10+10=120-10=130-50=140-50=200-40=300x6=280-7=240-8=3x90=200-5=4x10=120-3=400x9=810-9=5x7-20=256-5=214-7=125-2=21-4=73-9=280-4=360-9=320-8=180-6=630-9=4000-5=630-71600-2=2800-4=540-9=60x5=300-5=60x6=400-5=80x7=160-8=36+42=210-3=4x200=48-6x4=900+700=90+80=90+9=12-6=200-60=80-8=40x80=75-64=20x10=40-8=320-4=85-62=200-5=60x50=40-5-2=0-3=100-5=420-6=70x20=160-80=210-7=30x80=800-2=40x80=300-5=180-3=50x2=480-6=42+36=8x3-4=40x50=41+25=40x7=350-7=40x9=36+24=120-2=78-19=