(-1)+(+2)+(-3)+(+4)```````+(-1999)+(+2000)
(-1)+(+2)+(-3)+(+4)```````+(-1999)+(+2000)
1/1*2+1/2*3+1/3*4+.+1/1998*1999+1/1999*2000
1/1×2+1/2×3+1/3×4+...+1/1998×1999+1/1999×2000
1/2+2/3+3/4+.+1999/2000怎么算?
(2+4+6.+2000)-(1+3+5...+1999)
1-2+3-4+5-6+.+1999-2000+2001
1-2+3-4+5-6.+1999-2000+2001
1+2+3+4+.+1997+1998+1999+2000
3/(1!+2!+3!)+4/(2!+3!+4!)+...+2000/(1998!+1999!+2000!)
初一数学x/1*2+x/2*3+x/3*4+.x/1999*2000=1999
1.(2+5+8+...+2000)-1+4+7+...1999 (2000-2)/3+1-1=666
巧算(1/(2/3)/(3/4)/(4/5)/(5/6)/./(1999/2000)/(2000/2001)/(2001