Question

A pattern is given as:

1 = (1 × 2) ÷ 2
1 + 2 = (2 × 3) ÷ 2
1 + 2 + 3 = (3 × 4) ÷ 2
1 + 2 + 3 + 4 = (4 × 5) ÷ 2
1 + 2 + 3 + 4 + 5 = (5 × 6) ÷ 2 and so on
What will be the value of 1 + 2 + 3 + 4 + 5 + ....+ 20?

Answer 1

Would that be 20*21/2 ?