Column percentage calculator SASS mixin

n-of-m-columns.scss

/**
 * MIXIN n-of-m-columns
 * calculates the adequate percentage width and gutter percentage
 * @param $n: number of columns to calculate
 * @param $m number of total columns in the row
 **/
$gridGutter: 24px;
$defaultWidth: 984px;

@mixin n-of-m-columns($n:1, $m:3){
	$gutterCount: $m - 1;
	$gridGutterPercentage: $gridGutter / $defaultWidth * 100%;
	$columnWidth: ($defaultWidth - $gridGutter * ( $gutterCount ))  / $m;
	$columnWidthPercentage: $columnWidth / $defaultWidth * 100% ;
	width: ($columnWidth * $n + ($n - 1) * $gridGutter) / $defaultWidth * 100%;
	margin-left: $gridGutterPercentage;
}