Generated by SassMeister.com.

SassMeister-input.scss

// ----
// Sass (v3.4.12)
// Compass (v1.0.3)
// ----

$selector-lists: ();
$large-number-of-selectors: 100; // length($long-list);
$manage-number-of-selectors: 10;
@for $i from 1 through $large-number-of-selectors { 
  $the-selector: ".wrapper-#{$i} .child-#{$i}";
  //
  // Implementation details we don't care about below
  // This could be abstracted into a "distributor" function
  //
  $chunk: ceil($i / $manage-number-of-selectors);
  @if (length($selector-lists) < $chunk) {
    $selector-lists: append($selector-lists, ());
  }
  $selector-lists: set-nth($selector-lists, $chunk, append(nth($selector-lists, $chunk), $the-selector, comma));
}

// output the large set of selectors in managable chunks
@each $selector-list in $selector-lists {
  #{$selector-list} { a: b; }
}

SassMeister-output.css

.wrapper-1 .child-1, .wrapper-2 .child-2, .wrapper-3 .child-3, .wrapper-4 .child-4, .wrapper-5 .child-5, .wrapper-6 .child-6, .wrapper-7 .child-7, .wrapper-8 .child-8, .wrapper-9 .child-9, .wrapper-10 .child-10 {
  a: b;
}

.wrapper-11 .child-11, .wrapper-12 .child-12, .wrapper-13 .child-13, .wrapper-14 .child-14, .wrapper-15 .child-15, .wrapper-16 .child-16, .wrapper-17 .child-17, .wrapper-18 .child-18, .wrapper-19 .child-19, .wrapper-20 .child-20 {
  a: b;
}

.wrapper-21 .child-21, .wrapper-22 .child-22, .wrapper-23 .child-23, .wrapper-24 .child-24, .wrapper-25 .child-25, .wrapper-26 .child-26, .wrapper-27 .child-27, .wrapper-28 .child-28, .wrapper-29 .child-29, .wrapper-30 .child-30 {
  a: b;
}

.wrapper-31 .child-31, .wrapper-32 .child-32, .wrapper-33 .child-33, .wrapper-34 .child-34, .wrapper-35 .child-35, .wrapper-36 .child-36, .wrapper-37 .child-37, .wrapper-38 .child-38, .wrapper-39 .child-39, .wrapper-40 .child-40 {
  a: b;
}

.wrapper-41 .child-41, .wrapper-42 .child-42, .wrapper-43 .child-43, .wrapper-44 .child-44, .wrapper-45 .child-45, .wrapper-46 .child-46, .wrapper-47 .child-47, .wrapper-48 .child-48, .wrapper-49 .child-49, .wrapper-50 .child-50 {
  a: b;
}

.wrapper-51 .child-51, .wrapper-52 .child-52, .wrapper-53 .child-53, .wrapper-54 .child-54, .wrapper-55 .child-55, .wrapper-56 .child-56, .wrapper-57 .child-57, .wrapper-58 .child-58, .wrapper-59 .child-59, .wrapper-60 .child-60 {
  a: b;
}

.wrapper-61 .child-61, .wrapper-62 .child-62, .wrapper-63 .child-63, .wrapper-64 .child-64, .wrapper-65 .child-65, .wrapper-66 .child-66, .wrapper-67 .child-67, .wrapper-68 .child-68, .wrapper-69 .child-69, .wrapper-70 .child-70 {
  a: b;
}

.wrapper-71 .child-71, .wrapper-72 .child-72, .wrapper-73 .child-73, .wrapper-74 .child-74, .wrapper-75 .child-75, .wrapper-76 .child-76, .wrapper-77 .child-77, .wrapper-78 .child-78, .wrapper-79 .child-79, .wrapper-80 .child-80 {
  a: b;
}

.wrapper-81 .child-81, .wrapper-82 .child-82, .wrapper-83 .child-83, .wrapper-84 .child-84, .wrapper-85 .child-85, .wrapper-86 .child-86, .wrapper-87 .child-87, .wrapper-88 .child-88, .wrapper-89 .child-89, .wrapper-90 .child-90 {
  a: b;
}

.wrapper-91 .child-91, .wrapper-92 .child-92, .wrapper-93 .child-93, .wrapper-94 .child-94, .wrapper-95 .child-95, .wrapper-96 .child-96, .wrapper-97 .child-97, .wrapper-98 .child-98, .wrapper-99 .child-99, .wrapper-100 .child-100 {
  a: b;
}