巧算 9991+999.1+99.91+9.991
巧算 9991+999.1+99.91+9.991
9991+999.1+99.91+9.991
=(10000-9)+(1000-0.9)+(100-0.09)+(10-0.009)
=(10000+1000+100+10)-(9+0.9+0.09+0.009)
=11110-9.999
=11100.001
9991+999.1+99.91+9.991
=10000+1000+100+10-9-0.9-0.99-0.999
=11110-9.999
=11100.001
成功!!!!!!!!!!!!!!!
加油!!!!!!!!!!!!!!!
等比数列求和Sn=a1(1-q^n)/(1-q)=(a1-anq)/(1-q)
q=0.1,
所以代入运算就行
9991+9991*10^-1+9991*10^-2+9991*10^-3
=9991(10^0+10^-1+10^-2+10^-3)
=9991*1.111
=11100.001
10000+1000+100+10-9-0.9-0.09-0.009=11110-9.999=11110-10+0.001=11100+0.001=11100.001
9991+999.1+99.91+9.991
=(10000-9)+(1000-0.9)+(100-0.09)+(10-0.009)
=(10000+1000+100+10)-(9+0.9+0.09+0.009)
=11110-9.999
=11100.001
好累啊
等价于:
(10000-9)+(1000-0.90)+(100-0.09)+(10-0.009)
=10000+1000+100+10-(9+0.9+0.09+0.009)
=11100+10-9.999
=11100.001
(10000-9)+(1000-0.9)+(100-0.09)+(10-0.009)
=11110-9.999
=11100-(10-0.001)
=11100+0.001
=11100.001
9991+999.1+99.91+9.991
=(9991+9+999.1+0.9+99.91+0.09+9.991+0.009)-9.999
=(10000+1000+100+10)-9.999
=11100.001
9991+999.1+99.91+9.991
=9991+9991×0.1+9991×0.01+9991×0.001
=9991×(1+0.1+0.01+0.001)
=(10000-9)×1.111
=(10000-10+1)×1.111
=11110-11.11+1.111
=(11110+1.111)-11.11
=11111.111-11.11
=11100.001
9991+999.1+99.91+9.991
=9991+9991×0.1+9991×0.01+9991×0.001
=9991×(1+0.1+0.01+0.001)
=(10000-9)×1.111
=(10000-10+1)×1.111
=11110-11.11+1.111
=(11110+1.111)-11.11
=11111.111-11.11
=11100.001
加油呀!
努力!!!