Question

What is the sum of the sequence:
1+2+3+4...+1001

Answer 1

501501

Think of it like this...
1+999 = 1000
2+998 = 1000
3+997 = 1000
etc. How many of those do you have? and how many other things are left? you'll arrive at the above.

Answer 2

Awesome! Thank you

Answer 3

\[\sum _{i=1}^{1001} i=501501 \]