6 +0.25= | × = | ÷ =4 | ÷7= |
2.6-1 = | 8× = | 3-1.05= | 3.25×4= |
| 63+84= | 3.14×52= | 25× ×4= | 1 + +3 = |
6 +0.25=7, | × = , | ÷ = , | ÷7= , |
2.6-1 =0.9, | 8× = , | 3-1.05=1.95, | 3.25×4=13, |
| 63+84=300, | 3.14×52=78.5, | 25× ×4= , | 1 + +3 =5 . |
分析:63+84=6×6×6+84;3.14×52=3.14×(5×5),由此求解;
3.25×4先把3.15分解成3+0.25,再运用乘法分配律简算;
25×
×4运用乘法交换律简算;1
+
+3
运用加法交换律简算;其它题目根据运算法则直接求解.
点评:口算题目要求快速准确,能运用简算方法的要简算.
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