<?php
    function persistence($num){
        $result=0;
        $k = 1;
        while(abs($num) > 9){
            while (abs($num) > 0){
                $k *= ($num % 10);
                $num = (int)($num / 10);
            }
            $num = $k;
            $k = 1;
            $result++;
        }
    return $result;
    }
    //Вывод результата
    $a = 39;
    $res = persistence($a);
    echo "$a = $res\n";
    $a = 999;
    $res = persistence($a);
    echo "$a = $res\n";
    $a = 4;
    $res = persistence($a);
    echo "$a = $res\n";
    $a = mt_rand(-999999,999999);
    $res = persistence($a);
    echo "$a = $res\n";
?>

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