round a number to the nearest thousandth in ruby

To round a number to the nearest thousandth in Ruby, you can use the round method and pass 3 as an argument to specify the number of decimal places to round to. Here's an example:

main.rb
number = 3.14159265359
rounded_number = number.round(3)
puts rounded_number #=> 3.142
86 chars
4 lines

In this example, number is rounded to the nearest thousandth using the round method with an argument of 3. The resulting rounded_number is printed out to the console.