Question
Find the sum to the n terms:
5+55+555+.......
5+55+555+.......
Answers
Steve
1
1+11 = 12
1+11+111 = 123
So, for n terms, that ends up with
n*10^0 + (n-1)*10 + (n-2)*n^2
see whether you can arrive at the solution here:
http://www.wolframalpha.com/input/?i=sum(k%3D0..n-1)+(n-k)*10%5Ek
1+11 = 12
1+11+111 = 123
So, for n terms, that ends up with
n*10^0 + (n-1)*10 + (n-2)*n^2
see whether you can arrive at the solution here:
http://www.wolframalpha.com/input/?i=sum(k%3D0..n-1)+(n-k)*10%5Ek