Generated by SassMeister.com.

SassMeister-input.scss

// ----
// Sass (v3.3.0.rc.2)
// Compass (v1.0.0.alpha.17)
// ----

$usePercentage: true;

$snapTo: 640, 600, 560, 510, 460,
         320, 300, 240, 220, 210,
         200, 190, 180, 175, 170,
         165, 160, 155, 150, 140,
         135, 130, 125, 110, 105,
         100, 95, 90, 85, 80, 75,
         70;
         
$reduce: 640, 320, 300, 240;

@function unset($snapTo, $reduce){
  @for $i from 1 through length($snapTo) {
    $excludeMe: false;
    @each $unit in $reduce {
      @if($unit == nth($snapTo, $i)) {
        $excludeMe: true;
      }
    }
    @if ($excludeMe) {
      /* EXCLUDE #{nth($snapTo, $i)} */
      $snapTo: reject($snapTo, #{nth($snapTo, $i)});
    }
  }
  @return $snapTo;
}

$yahoo : unset($snapTo, $reduce);

@for $i from 1 through length($yahoo) {
  /* #{nth($yahoo, $i)} */
}

SassMeister-output.css

/* 640 */
/* 600 */
/* 560 */
/* 510 */
/* 460 */
/* 320 */
/* 300 */
/* 240 */
/* 220 */
/* 210 */
/* 200 */
/* 190 */
/* 180 */
/* 175 */
/* 170 */
/* 165 */
/* 160 */
/* 155 */
/* 150 */
/* 140 */
/* 135 */
/* 130 */
/* 125 */
/* 110 */
/* 105 */
/* 100 */
/* 95 */
/* 90 */
/* 85 */
/* 80 */
/* 75 */
/* 70 */