数学题简便方法计算

1、195168÷912+374×109-5820
=214+374×109-5820
=214+374×(100+10-1)-5820
=214+37400+3740-374-5820
=41354-6194
=35160
2、0.35-[10-(0.2+6.37÷0.7)]×0.5
=0.5×0.7-[10-(0.2+9.1)]×0.5
=0.5×[0.7-(10-9.3)]
=0.5×0=0
3、（25×11×125）×（9×8×4）
=25×11×125×9×8×4
=(25×4)×(125×8)×(11×9)
=100×1000×99
=9900000
4、999.9+99.9+0.2+0.9+9.9+0.2
=(1000-0.1)+(100-0.1)+0.2+(1-0.1)+(10-0.1)+0.2
=1000+100+1+10-0.1×4+(0.2+0.2)
=1111-0.4+0.4
=1111
5、6.9×0.125×1.75÷（2.3×1/8×1/4）
=69/10×(1/8)×(7/4)÷[(23/10)×(1/8)×(1/4)]
=[(23×3×7)/(10×8×4)]÷[23/(10×8×4)]
=[(23×3×7)/(10×8×4)]×[(10×8×4)/23]
=3×7=21
6、3.5×1.25+1.25×2.7+3.8×1.25
=1.25×(3.5+2.7+3.8)
=1.25×10
=12.5