数学简便方法,每题好简便方法.1-4583-999 2- 6999995+599996+49997+3998+89 3- 550000/121*11 4- 123*456/789/456*789/123 5- 7/1.25 6- 8.7*9.9 7- 1.25*66.875+1250*0.054375+125*6.7875 8- 5.5*101+45*9.9 9- 98989898*99999999/1010101/11111111 10- 1

来源:学生作业帮助网 编辑:作业帮 时间:2024/05/14 04:04:45

数学简便方法,每题好简便方法.
1-4583-999 2- 6999995+599996+49997+3998+89 3- 550000/121*11 4- 123*456/789/456*789/123 5- 7/1.25 6- 8.7*9.9 7- 1.25*66.875+1250*0.054375+125*6.7875 8- 5.5*101+45*9.9 9- 98989898*99999999/1010101/11111111 10- 111...(2013个1)*999...(2013个9)
第一题:4583-999 第二题:6999995+599996+49997+3998+89 第三题:550000/121*11 第四题:7/1.25 第五题:8.7*9.9 第六题:1.25*66.875+1250*0.54375+125*6.7875 第七题:5.5*101+45*9.9 第八题:98989898*99999999/1010101/11111111 第九题:111...(2013个1)*999...(2013个9) 第十题:123*456/789/456*789/123 (每题说下用的什么简便方法好吗?是每题!)还有其他哪种简便方法,举个列子.

4583-999
=4583-(1000-1)
=4583-1000+1
=3583+1
=3584
6999995+599996+49997+3998+89
=(7000000-5)+(600000-4)+(50000-3)+(4000-2)+(100-11)
=(7000000+600000+50000+4000+100)-(5+4+3+2+11)
=7654100-25
=7654075
550000÷121×11
=550000÷(11×11)×11
=(550000÷11)×(11÷11)
=50000×1
=50000
7÷1.25
=(7×8)÷(1.25×8)
=56÷10
=5.6
8.7×9.9
=8.7×(10-0.1)
=8.7×10-8.7×0.1
=87-0.87
=86.13
1.25×66.875+1250×0.054375+125×6.7875
=125×0.66875+125×0.54375+125×6.7875
=125×(0.66875+0.54375+6.7875)
=125×8
=1000
5.5×101+45×9.9
=55×10.1+45×9.9
=55×(10+0.1)+45×(10-0.1)
=55×10+55×0.1+45×10-45×0.1
=10×(55+45)+0.1×(55-45)
=10×100+0.1×10
=1000+1
=1001
98989898×99999999÷1010101÷11111111
=(98989898÷1010101)×(99999999÷11111111)
=98×9
=98×(10-1)
=98×10-98×1
=980-98
=882
111.(2013个1)×999.(2013个9)
=111.(2013个1)×(100.(2014个0)-1)
=111.(2013个1)×100.(2014个0)-111...(2013个1)×1
=111...(2013个1)000.(2014个0)-111...(2013个1)
=111...(2012个1)9888...(2012个8)9
123×456÷789÷456×789÷123
=(123÷123)×(456÷456)×(789÷789)
=1×1×1
=1