3v4l.org

run code in 300+ PHP versions simultaneously
<?php foreach(range(0,9) as $n){ echo "$n -> ",(10**$n-1)," ",(10**$n-1)/9," ",(10**$n-1)/9*$n,"\n"; }
Output for 7.1.0 - 7.1.20, 7.2.0 - 7.2.33, 7.3.16 - 7.3.33, 7.4.0 - 7.4.33, 8.0.0 - 8.0.30, 8.1.0 - 8.1.33, 8.2.0 - 8.2.29, 8.3.0 - 8.3.27, 8.4.1 - 8.4.14
0 -> 0 0 0 1 -> 9 1 1 2 -> 99 11 22 3 -> 999 111 333 4 -> 9999 1111 4444 5 -> 99999 11111 55555 6 -> 999999 111111 666666 7 -> 9999999 1111111 7777777 8 -> 99999999 11111111 88888888 9 -> 999999999 111111111 999999999
preferences:
154.12 ms | 408 KiB | 5 Q