> For the complete documentation index, see [llms.txt](https://trizen.gitbook.io/sidef-lang/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://trizen.gitbook.io/sidef-lang/programming_tasks/s/sum_of_a_series.md).

# Sum of a series

```ruby
say sum(1..1000, {|n| 1 / n**2 })
```

Alternatively, using the *reduce{}* method:

```ruby
say (1..1000 -> reduce { |a,b| a + (1 / b**2) })
```

#### Output:

```
1.64393456668155980313905802382221558965210344649
```