Question

1*2+2*3+3*4+4*5+......+99*100=？

Answer 1

1*2+2*3+3*4+4*5+......+99*100
=1+2+3+------+99+(1^2+2^2+3^2+-------+99^2)
=4950+99*100*199/6
=4950+328350
=333300
http://zhidao.baidu.com/question/88781530.html

Answer 2

a=[1:99];
b=[2:100];
s=a.*b;
ss=sum(s)

输出结果：ss =

333300

Answer 3

分母是相邻两个自然数之积吧，原式=3×[1/1*2+1/2*3+...+1/99*100]=3×[(1-1/2)+(1/2-1/3)+(1/3-1/4)+...(1/99-1/100)]=3×[1-1/100]=...