上海数学题(五年级)

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<