Generated by SassMeister.com.

SassMeister-input.scss

// ----
// Sass (v3.4.9)
// Compass (v1.0.1)
// ----

$granularity: 3;

@for $i from 1 through $granularity {
  @for $j from 1 through $i {
    .col-#{$j}-#{$i} {
      width: $j/$i * 100%;    
    }
  }
}

SassMeister-output.css

.col-1-1 {
  width: 100%;
}

.col-1-2 {
  width: 50%;
}

.col-2-2 {
  width: 100%;
}

.col-1-3 {
  width: 33.33333%;
}

.col-2-3 {
  width: 66.66667%;
}

.col-3-3 {
  width: 100%;
}