JavaScript - painless decimal multiplication

JavaScript has a bug when multiplying decimals, try yourself:

0.1 * 0.2
> 0.020000000000000004 // NodeJS 0.8

The way to correct this is to multiply the decimals before multiple their values, try yourself:

( 0.1 * 10 + 0.2 * 10 ) / 10
> 0.3

You can create a function for this:

function multdec ( val1, val2 ) {
    return ( val1 * 10 + val2 * 10 ) / 10;
}

You can extend the Math object:

Math.multdec = function ( val1, val2 ) {
    return ( val1 * 10 + val2 * 10 ) / 10;
}

Now you can call this operation in two ways:

multdec( val1, val2 );  // 0.3
// or
Math.multdec ( val1, val2 );  // 0.3