Thursday
March 23, 2017

Post a New Question

Posted by on Saturday, June 7, 2014 at 8:04pm.

1+2+3+...+n=(1+n)+(2+(n-1))+(3+(n-2))+...
=(1+n)+(1+n)+(1+n)+...

How many copies of n+1 are in there in the second line?
with n=6 and n=7

  • Number Theory - , Saturday, June 7, 2014 at 10:47pm

    Since the n numbers are divided up in pairs, I'd say n/2 copies.

    Hence the formula for the sum: n(n+1)/2

    Technically, that's [n+1]/2 where [] is the greatest-integer function.

Answer This Question

First Name:
School Subject:
Answer:

Related Questions

More Related Questions

Post a New Question