Brain Test Level 426
Question & Solution
The puzzle asks you to solve the equation 1 + 2 + 3 + ... + 100.
How to Solve
This is a classic arithmetic series problem, often associated with young Gauss. The easiest way to solve this is to use the formula for the sum of the first N integers: S = N * (N + 1) / 2.
Here, N = 100.
Calculation: 100 * (100 + 1) / 2 = 100 * 101 / 2 = 50 * 101 = 5050.
The answer is 5050.
DIFFICULTY
Medium
PRO TIP
Pair the first number (1) with the last number (100). How many pairs of 101 do you have?