# Php > Algorithms Code Examples

## Function to convert Arabic numbers into Roman Numerals

``` Function to convert Arabic numbers into Roman Numerals Here's a little function I put together to convert an Arabic number between 0 and 9,999 to a Roman Numeral. Initial testing went well, but it has not been fully tested yet. <? function to_roman(\$num) { // Function to convert an arabic number (\$num) to a roman numeral. \$num must be between 0 and 9,999 if (\$num < 0 || \$num > 9999) { return -1; } // out of range \$r_ones = array(1=> "I", 2=>"II", 3=>"III", 4=>"IV", 5=>"V", 6=>"VI", 7=>"VII", 8=>"VIII", 9=>"IX"); \$r_tens = array(1=> "X", 2=>"XX", 3=>"XXX", 4=>"XL", 5=>"L", 6=>"LX", 7=>"LXX", 8=>"LXXX", 9=>"XC"); \$r_hund = array(1=> "C", 2=>"CC", 3=>"CCC", 4=>"CD", 5=>"D", 6=>"DC", 7=>"DCC", 8=>"DCCC", 9=>"CM"); \$r_thou = array(1=> "M", 2=>"MM", 3=>"MMM", 4=>"MMMM", 5=>"MMMMM", 6=>"MMMMMM", 7=>"MMMMMMM", 8=>"MMMMMMMM", 9=>"MMMMMMMMM"); \$ones = \$num % 10; \$tens = (\$num - \$ones) % 100; \$hundreds = (\$num - \$tens - \$ones) % 1000; \$thou = (\$num - \$hundreds - \$tens - \$ones) % 10000; \$tens = \$tens / 10; \$hundreds = \$hundreds / 100; \$thou = \$thou / 1000; if (\$thou) { \$rnum .= \$r_thou[\$thou]; } if (\$hundreds) { \$rnum .= \$r_hund[\$hundreds]; } if (\$tens) { \$rnum .= \$r_tens[\$tens]; } if (\$ones) { \$rnum .= \$r_ones[\$ones]; } return \$rnum; } // function to_roman(\$num) ?> ```