上海数学题(五年级)

问题描述：

1. 18.3乘0.25+5.3乘2.5+7.13乘7.5
2.12.5乘0.76乘0.4乘8乘2.5
3.1990乘198.9-1989乘198.8
4.(632乘276-524)除(632乘275+108)
如果很好,另外加分!很多很多哦!

问题解答：

1.18.3*0.25+5.3*2.5+7.13*7.5
=1.83*2.5+5.3*2.5+21.39*2.5
=2.5*(1.83+5.3+21.39)
=2.5*28.52
=71.3
2.12.5*0.76*0.4*8*2.5
=(12.5*8)*0.76*(0.4*2.5)
=100*0.76*1
=76
3.1990*198.9-1989*198.8
=1990*198.9-198.9*1988
=198.9*(1990-1988)
=198.9*2
=397.8
4.(632*276-524)/(632*275+108)
=(632*275+632-524)/(632*275+108)
=(632*275+108)/(632*275+108)
=1

1. 71.3
2. 76
3. 397.8
4. 1
是要求简算吗？那就利用乘法结合律、分配律、交换律就可以了

18.3*0.25+5.3*2.5+7.13*7.5=1.83*2.5+5.3*2.5+21.39*2.5
=2.5(1.83+5.3+21.39)=71.3
12.5*0.76*0.4*8*2.5=12.5*8*2.5*0.4*0.76=76
1989(199-198.8)=397.8
(632*275+108)/(632*276-524)=1

1. 原式=2.5×（1.83+5.3+7.13×3）=2.5×（713/25）=71.3
2. 原式=12.5×8×0.4×2.5×0.76=76
3. 原式=1989×（199-198.8）=397.8
4. 原式=（632×275+632-524）÷（632×275+108）=1

1.18.3*0.25+5.3*2.5+7.13*7.5
=1.83*2.5+5.3*2.5+21.39*2.5
=2.5*(1.83+5.3+21.39)
=2.5*28.52
=71.3
2.12.5*0.76*0.4*8*2.5
=(12.5*8)*0.76*(0.4*2.5)
=100*0.76*1
=76
3.1990*198.9-1989*198.8
=1990*198.9-198.9*1988
=198.9*(1990-1988)
=198.9*2
=397.8
4.(632*276-524)/(632*275+108)
=(632*275+632-524)/(632*275+108)
=(632*275+108)/(632*275+108)
=1
这么好，赶快追加分。

1、18.3×0.25+5.3×2.5+7.13×7.5
=(1.83×2.5+5.3×2.5)+7.13×(2.5×3)
=7.13×2.5+7.13×3×2.5
=7.13×4×2.5
=7.13×(2.5×4)
=7.13×10
=71.3
2、12.5×0.76×0.4×8×2.5
=(12.5×8)×(0.4×2.5)×0.76
=100×1×0.76
=76
3、1990×198.9-1989×198.8
=199×1989-198.8×1989
=(199-198.8)×1989
=0.2×1989
=397.8
4、（632×276-524）÷（632×275+108）
=[（632×275）+632×1-524]÷（632×275+108）
=(632×275+108)÷(632×275+108)
=1