Question

Find the arithmetic sequence
1+2+3+4+....+1002

Answer 1

502503

Explanation:

formula is

Sn = n/2 * (2a1 + (n - 1 ) * d)

S is the sum

a1 is the first number which is 1

d is the difference between each number

n is the last number of terms

S1002 = 1002/2 * ((2 * 1002) + (1002 - 1) * 1002) = 502503