<?php
$string = "087777807209"; // Original string
$replacement = "62"; // What you want to replace the last character with
// The final string
$final = $replacement.substr($string, 0, 1);
echo $final;
Warning: PHP Startup: Unable to load dynamic library 'sodium.so' (tried: /usr/lib/php/8.3.5/modules/sodium.so (libsodium.so.23: cannot open shared object file: No such file or directory), /usr/lib/php/8.3.5/modules/sodium.so.so (/usr/lib/php/8.3.5/modules/sodium.so.so: cannot open shared object file: No such file or directory)) in Unknown on line 0
620