文档介绍：-= += -= 720÷800=
+= -= 17×300= -=
+= ×= += +=
+= += -= ÷5=
-= += ×100= -=
2+= -= += +=
÷70= +3= += ÷25=
+1= -= += +=
3+= ÷9= -= -5=
×9= -= -= +=
1-= += += +4=
4-= += += +=
÷40= 53÷100= += ×80=
÷10= += 7×= ×100=
-= -= ×10= 10+=
1-= ×1000= += +=
×100= -= -= 63÷100=
-= += 80÷1000= +=
-= 0×= -= +=
+= 5+= 1-= +=
+= += += 1-=
8-= -= += +=
-= -= -= -=
10+= -= += +=
-= 1-=
-= -= -= +=
-= -= += ÷11=
×10= ×7=     ÷5= 8×+3=
×= +21= ÷= ÷=
501-98= ×= 110÷100= ×9=
×10= 125×7+125= ×5= ×7=
÷= ÷= += 480+199=
63÷= 4×= += ×7=
10÷8= += ×8= ÷=
×3= ×= 100÷200= ×=
×= ÷70= ×= ÷7÷=
5×= ×4×= 50× = ÷=
÷3= 100××