Function

// Function

$width: 200px;

.element {
  width: $width;
  height: half($width);
  top: calculate(100px, 200px, 50px);
}

/// Function To Get Element Height
///
/// @param {size}
/// Element Width
/// @return {int}
/// Return Element Height => Width / 2

@function half($size) {
  @return $size / 2;
}

@function calculate($sizes...) {
  $total: 0;
  @each $size in $sizes {
    $total: $total + $size;
  }
  @return $total;
}