# how can i make a floating device have 8 digits?

If you’re looking to truncate your numbers to exactly 8 digits (not counting the decimal point):

function myTrunc( \$n ) {
\$first9 = substr( \$n, 0, 9 ); // The first 9 chars
\$hasDecimal = ( FALSE !== strpos( \$first9, '.' ) ); // Whether it contains a decimal
\$r = substr( \$first9, 0, \$hasDecimal ? 9 : 8 ); // Get first 8 (or 9 if there is a decimal)
return trim( \$r, '.' ); // Trim any trailing decimal (so 12345678. becomes 12345678)
}

\$n1 = 1.234567891011;
\$n2 = 12.34567891011;
\$n3 = 1234567891011;
\$n4 = 1234567.891011;
\$n5 = 12345678.91011;
\$n6 = 123456789.1011;

echo "\$n1 truncates to " . myTrunc( \$n1 ) . "\n"; // 1.2345678
echo "\$n2 truncates to " . myTrunc( \$n2 ) . "\n"; // 12.345678
echo "\$n3 truncates to " . myTrunc( \$n3 ) . "\n"; // 12345678
echo "\$n4 truncates to " . myTrunc( \$n4 ) . "\n"; // 1234567.8
echo "\$n5 truncates to " . myTrunc( \$n5 ) . "\n"; // 12345678
echo "\$n6 truncates to " . myTrunc( \$n6 ) . "\n"; // 12345678