(7 votes, average: 5.00 out of 5)

## Source Code for Master Lock Combination Calculator

Code to calculate possible combinations for a Master combination lock given the last number in the combination. This source is in PHP.

```<table summary="Possible Master Lock Combinations">
<caption>Possible Combinations</caption>

<?php
\$default_c3 = 0;
\$c3 = (int) isset(\$_GET["last_comb"])? \$_GET["last_comb"] : \$default_c3;
if (\$c3<0 || \$c3>39) \$c3 = \$default_c3;

for (\$c2=(\$c3+2)%4; \$c2<40; \$c2+=4)
{
print "<tr>";
for (\$c1=\$c3%4; \$c1<40; \$c1+=4)
{
if (\$c1-\$c2==2 or \$c1-\$c2==6 or \$c2-\$c1==38 or \$c2-\$c1==34 or abs(\$c3-\$c2)%36==2)
echo "<td> </td>";
else
echo "<td>\$c1 - \$c2 - \$c3</td>";
}
print "</tr>\r\n";
}
?>
</table>

```

## Discussion

### 11 Responses to “Source Code for Master Lock Combination Calculator”

1. So nice to have it online. I have the Excel file if anyone wants it?

Posted by Dan Casta | July 8, 2012, 5:21 AM
• Hi Dan,

I think it would be great to offer the excel file for download. Or you can give me the URL and I’ll link to it.

-Mike

Posted by Mike | July 9, 2012, 7:56 PM
2. Help! I have a Master Lock and forgot the combo! Serial Number 8000148

Posted by Jennifer | October 20, 2011, 8:24 AM
3. I’m iprmeessd! You’ve managed the almost impossible.

Posted by Lorena | April 16, 2011, 8:16 AM
4. How did you find this formula for master locks?

Posted by Rob | November 14, 2010, 11:39 PM
• It was based on the physical limitations of the lock. One such limitation was the mechanical resolution was 1 or 2 numbers away from the published combination. So, if the published combo was 4-32-16, for example, 5-32-16 would work as well. Some may describe this as sloppiness in the lock mechanics.

Posted by Mike | January 26, 2011, 11:52 PM
5. What about for a combination lock with numbers from 0 to 49?

Posted by matt | June 19, 2010, 8:22 PM
6. Can you make it so that I can run this program on your website? I don’t have php on my computer. This would be an excellent utility for they iPhone.

Posted by TJ Mathews | September 27, 2009, 3:12 PM