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六、计算下面各题,怎样简便就怎样计算。(每题3分,共27分)
$98+(64+102)$
$295-25-75$
$99×66$
$4×135×5$
$2500÷2÷25$
$86×25-86×15$
$3.5+4.9+2.5$
$6.18-(2.32+1.18)$
$19.1-(5.6-3.24)$
$98+(64+102)$
$295-25-75$
$99×66$
$4×135×5$
$2500÷2÷25$
$86×25-86×15$
$3.5+4.9+2.5$
$6.18-(2.32+1.18)$
$19.1-(5.6-3.24)$
答案
1. 98+(64+102)=264
2. 295-25-75=195
3. 99×66=6534
4. 4×135×5=2700
5. 2500÷2÷25=50
6. 86×25-86×15=860
7. 3.5+4.9+2.5=10.9
8. 6.18-(2.32+1.18)=2.68
9. 19.1-(5.6-3.24)=16.74
2. 295-25-75=195
3. 99×66=6534
4. 4×135×5=2700
5. 2500÷2÷25=50
6. 86×25-86×15=860
7. 3.5+4.9+2.5=10.9
8. 6.18-(2.32+1.18)=2.68
9. 19.1-(5.6-3.24)=16.74
计算:0.9+9.9+99.9+999.9+9999.9+99999.9。(共5分)
答案
$0.9+9.9+99.9+999.9+9999.9+99999.9$
$=(1-0.1)+(10-0.1)+(100-0.1)+(1000-0.1)+(10000-0.1)+(100000-0.1)$
$=111111-0.6$
$=111110.4$
$=(1-0.1)+(10-0.1)+(100-0.1)+(1000-0.1)+(10000-0.1)+(100000-0.1)$
$=111111-0.6$
$=111110.4$
