<?php
$dec = 0.625;
 
$hours = $dec * 24;
 
function convertTime($dec)
{
    // start by converting to seconds
    $seconds = ($dec * 3600);
    // we're given hours, so let's get those the easy way
    $hours = floor($dec);
    // since we've "calculated" hours, let's remove them from the seconds variable
    $seconds -= $hours * 3600;
    // calculate minutes left
    $minutes = floor($seconds / 60);
    // remove those from seconds as well
    $seconds -= $minutes * 60;
    // return the time formatted HH:MM:SS
    return lz($hours).":".lz($minutes).":".lz($seconds);
}
 
// lz = leading zero
function lz($num)
{
    return (strlen($num) < 2) ? "0{$num}" : $num;
}
 
echo convertTime($hours);

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