Here's the original proposal, with rationale. https://wiki.php.net/rfc/numeric_literal_separator https://wiki.php.net/rfc/numeric_literal_separator TL;DR: su

Here's the original proposal, with rationale. https://wiki.php.net/rfc/numeric_literal_separator https://wiki.php.net/rfc/numeric_literal_separator TL;DR: supposedly better readability.