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用简便方法计算 4538+3998 3.2×10.1 38×99+38 7/15÷5+8/15×1/5 1-0.225÷

来源:学生作业帮 编辑:神马作文网作业帮 分类:数学作业 时间:2024/11/10 11:21:10
用简便方法计算 4538+3998 3.2×10.1 38×99+38 7/15÷5+8/15×1/5 1-0.225÷0.9-0.75 65×65/66
2.5×3.2×12.5
用简便方法计算 4538+3998 3.2×10.1 38×99+38 7/15÷5+8/15×1/5 1-0.225÷
4538+3998
=4538+4000-2
=8538-2
=8536

3.2×10.1
=3.2×10+3.2×0.1
=32+0.32
=32.32

38×99+38
=38×(1+99)
=38×100
=3800
7/15÷5+8/15×1/5
=(7/15+8/15)×1/5
=1/5

1-0.225÷0.9-0.75
1-(0.25+0.75)
=1-1
=0

65×65/66
=65×(1-1/66)
=65-65/66
=64又1/66
2.5×3.2×12.5
=2.5×4×(0.8×12.5)
=10×10
=100