Look for a pattern in the expressions shown below. Use the pattern to write an expression for the sum of the whole numbers from 1 to n. Then find the sum of the whole numbers from 1 to 50.

Question

1+2= 2•3/2 1+2+3= 3•4/2 1+2+3+4= 4•5/2

Answer 1

1+...+n = n(n+1)/2