If you want to display a 3-digit delimiter

Use the to_s (: delimited) method
Add require at the beginning of the file to use the above method active_support is a component of Ruby on Rails that allows you to use various methods

`num.rb`


require "active_support/core_ext/numeric/conversions"

10000.to_s(:delimited)
# => "10,000"

Details can be found on the Active Support page of the Rails Guide (6.3 Formatting) https://railsguides.jp/active_support_core_extensions.html#%E6%9B%B8%E5%BC%8F%E8%A8%AD%E5%AE%9A

Afterword

When I was looking for a 3-digit display method "It seems that the .to_s (: delimited) method can be used to separate numbers into 3 digits!" I didn't know that require was needed and encountered the following error.

in `to_s': no implicit conversion of Symbol into Integer (TypeError)

I can use to_s normally, but when I add (: delimited), I get an error and am in trouble. Therefore, if you use the to_s (: delimited) method with ruby, you must require to enable active_support.

I would like to take this opportunity to learn and utilize other useful methods of active_support.

Achieve 3-digit delimited display in Ruby

If you want to display a 3-digit delimiter

num.rb

Afterword

`num.rb`