1+2+3+4··· ···+78+79=?
1+2+3+4··· ···+78+79=?
1+2+3+4+······+78+79+80
1+2++3+··········+10000=
俗语和名句的填空1······,自知之明.2······,行必果.3工欲善其事,······.4临渊羡鱼,······.
(1-2)×(2-3)×(3-4)×······×(19-20)=
1\(2\3)\(3\4)······\(18\19)\(19\20)=
1+2+3+4+5+6······38+39=?
计算1-2+3-4+5-6+······-98+99=
1+2+3+4+5······+100+101=几
1/3+2/3=1,但0.333···+0.666···=0.999···,为神马?额······谁能解释一下·····
根据1+2+3+4+······+n=n(n+1)/2 计算2+4+6+····+200
数学题1*2分之一+2*3分之一+3*4分之一+···············+99*100分之一=( )