php convert number with k on the end to full number

PHP

// convert_short_number function
function convert_short_number($snum) {
  $map = array("k" => 1000,"m" => 1000000,"b" => 1000000000,"t" => 1000000000000);
  $money = $snum;
  list($value,$suffix) = sscanf($money, "%f%s");
  $final = $value*$map[$suffix];
  return($final);
}

// examples
// thousands test or k, why is it not t for thousands...?
$k_test = "23.8k";
$k_test_result = convert_short_number($snum = $k_test);
echo "<p>Converting $k_test to $k_test_result</p>";

// million test
$mil_test = "11.3m";
$mil_test_result = convert_short_number($snum = $mil_test);
echo "<p>Converting $mil_test to $mil_test_result</p>";

// billion test
$bil_test = "136.87b";
$bil_test_result = convert_short_number($snum = $bil_test);
echo "<p>Converting $bil_test to $bil_test_result</p>";

// trillion test
$tril_test = "158.293t";
$tril_test_result = convert_short_number($snum = $tril_test);
echo "<p>Converting $tril_test to $tril_test_result</p>";