题目内容
= 0×= 1÷= ×=
1-= = = =
30-16= 52-9= 35+19= 85-20=?
68-25= 40-26= 86-6= 70-15=?
47+20= 50-38= 100-52= 65-23=?
52-18= 63-7= 79-43= 46+18=
2×4= 3×5= 4×6=?
20×4= 30×5= 40×6=?
200×4= 300×5= 400×6=?
比较：每组算式有什么相同点？你能发现口算的秘密吗？??
想想：怎样才能快速算出“400×5”这样算式的结果？??
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= 0×= 1÷= ×== = = =