Using REGEXREPLACE to insert commas into values in Google Sheets

Question

How do I go about using REGEXREPLACE to insert commas into values in Google Sheets? Example:

cell A1 = 1234567890

expected output in B1 = 1,234,567,890

edit: The intention would be so that the user would not need to format anything themselves. This issue is from a template I'm doing up, sample sheet here - https://docs.google.com/spreadsheets/d/1n-KXqcSpx_DpvrOv9A4UsKn1amGGEUCpyzWWDphWdJY/edit?usp=sharing

user_5632629 · Answer

try:

=TEXT(A1; "#,###,###,##0")

user_15019380 · Answer

Try

=A1

and change the format to

#,##0

user_16720176 · Answer

To insert commas into values in Google Sheets, I recommend: