# Sum

How do you sum up all the numbers in an array or list? With linq, we can use the .Sum method.

# Basic example

Live example: https://dotnetfiddle.net/tvUKY5

var scores = new[] { 87, 56, 33, 20, 11, -10, -50 };

int totalScores = scores.Sum();

// output: 147

# Sum with Func

If you ever need to perform a summation of numbers but also need to perform a transformation on each number before the summation, then you can use the Sum with a Func.

The example below performs a division of 100 to each number - this is shown in the lambda expression i => i/100d

Live example: https://dotnetfiddle.net/dt0EJN

var scores = new[] { 87, 56, 33, 20, 11, -10, -50 };

// divide each number by 100 before summing.
double sum = scores.Sum(i => i/100d);

// output 1.47